Following is taken from Wickipedia:

The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt region is also termed the main belt to distinguish it from other concentrations of minor planets within the Solar System, such as the Kuiper belt and scattered disk.

More than half the mass within the main belt is contained in the four largest objects: Ceres, 4 Vesta, 2 Pallas, and 10 Hygiea. All of these have mean diameters of more than 400 km, while Ceres, the main belt's only dwarf planet, is about 950 km in diameter.^[1][2][3][4] The remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that multiple unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can form an asteroid family whose members have similar orbital characteristics and compositions. Collisions also produce a fine dust that forms a major component of the zodiacal light. Individual asteroids within the main belt are categorized by their spectra, with most falling into three basic groups: carbonaceous (C-type), silicate (S-type), and metal-rich (M-type).

The asteroid belt formed from the primordial solar nebula as a group of planetesimals, the smaller precursors of the planets. Between Mars and Jupiter, however, gravitational perturbations from the giant planet imbued the planetesimals with too much orbital energy for them to accrete into a planet. Collisions became too violent, and instead of sticking together, the planetesimals shattered. As a result, most of the main belt's mass has been lost since the formation of the Solar System. Some fragments can eventually find their way into the inner Solar System, leading to meteorite impacts with the inner planets. Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits.

M-type asteroids are asteroids of unknown composition; they are moderately bright (albedo 0.1–0.2). Some, but not all, are made of nickel-iron, either pure or mixed with small amounts of stone. These are thought to be pieces of the metallic core of differentiated asteroids that were fragmented by impacts. They are thought to be the source of iron meteorites.

There are also M-types whose composition is uncertain. For example, 22 Kalliope has an accurately known density that is far too low for a solid metallic object or even a metal rubble pile: a rubble pile of iron-nickel metal would need about 70% porosity which is inconsistent with packing considerations. Kalliope and 21 Lutetia have features in their spectra which appear to indicate the presence of hydrated minerals^[1] and silicates,^[2] anomalously low radar albedos inconsistent with a metallic surface,^[3] as well as characteristics more in common with C-type asteroids. A variety of other M-type asteroids do not fit well into a metallic body picture.

M-type spectra are flat to reddish and usually devoid of large features, although subtle absorption features longward of 0.75 µm and shortward of 0.55 µm are sometimes present.^[4]

16 Psyche is the largest M-type asteroid, and does appear to be metallic. 21 Lutetia, an anomalous, probably nometallic body, will be the first M-type asteroid to be imaged by a spacecraft when the Rosetta space probe visits it on July 10, 2010. Another M-type, 216 Kleopatra, was imaged by radar by the Arecibo Observatory in Puerto Rico and has a dog bone-like shape.

M type was one of three basic asteroid types in early classifications (the others being the S and C types), and was thought to indicate a metallic body.

184 Dejopeja is a large M-type Main belt asteroid.

A three-dimensional model of 184 Dejopeja based on its light curve.

Taken from Wikipedia:

Alexandra is a very large and dark main belt asteroid. It was discovered by H. Goldschmidt on September 10, 1858 and named after the German explorer Alexander von Humboldt. On May 17, 2005 this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km)

Several images were blink-processed in Visual Pinpoint to see the relative movement of the asteroid compared to the stationary stars.

Eunomia asteroid (2-29-2008)

Taken from Wikipedia:

Eunomia is a very large asteroid in the inner main asteroid belt. It is the largest of the stony (S-type) asteroids, and somewhere between the 8th to 12th largest Main Belt asteroid overall (uncertainty in diameters causes uncertainty in its ranking). It is also the largest member of the Eunomia family of asteroids.

Eunomia appears to be an elongated but fairly regularly shaped body, with what appear to be four sides of differing curvature and noticeably different average compositions.^[2] Its elongation led to the suggestion that Eunomia may be a binary object. However, this has been refuted.^[3] It is a retrograde rotator with its pole pointing towards ecliptic coordinates (?, ?) = (-65°, 2°) with a 10° uncertainty.^[2][3] This gives an axial tilt of about 165°.

Like other true members of the family, its surface is composed of silicates and some nickel-iron, and is quite bright. Calcium-rich pyroxenes and olivine, along with nickel-iron metal have been detected on Eunomia's surface. Spectroscopic studies suggest that Eunomia has regions with differing composition. A larger region dominated by olivine, which is pyroxene poor and metal rich, and another somewhat smaller region on one hemisphere (the less pointed end) that is noticeably richer in pyroxene,^[2] and has a generally basaltic composition.^[7]

This composition indicates that the parent body was likely subject to magmatic processes, and became at least partially differentiated under the influence of internal heating in the early period of the Solar System. The range of compositions of the remaining Eunomia family members, formed by a collision of the common parent body, is large enough to encompass all the surface variations on Eunomia itself. Interestingly, the majority of smaller family members are more pyroxene rich than Eunomia's surface, and contain very few metallic (M-type) bodies.

Altogether these lines of evidence suggest that Eunomia is the central remnant of the parent body of the Eunomia family that was stripped of most of its crustal material by the family-forming impact, but perhaps not disrupted. However, there is uncertainty over Eunomia's internal structure and relationship to the family parent body. Computer simulations of the collision^[8] are more consistent with Eunomia being a re-accumulation of most of the fragments of a completely shattered parent body. Coversely again, Eunomia's quite high density would indicate that it is not a rubble pile after all. Whetever the case in this respect, it appears that any metallic core region, if present, has not been exposed.

An older explanation of the compositional differences, that Eunomia is a mantle fragment of a far larger parent body (with a bit of crust on one end, and a bit of core on the other) appears to be ruled out by studies of the mass distribution of the entire Eunomia family of asteroids. These indicate that the largest remaining fragment (that is, Eunomia) should have about 70% of the mass of the parent body,^[9] which is consistent with Eunomia being a central remnant, with the crust and a part of the mantle stripped off.

These indications are also in accord with fresh mass determinations which indicate that Eunomia has a typical density for mostly intact stony asteroids, and not the anomalously low "rubble pile" density of ~1 g/cm³ that had been obtained earlier.

Eunomia has been observed occulting stars three times. It has a mean opposition magnitude of +8.5,^[10] about equal to the mean brightness of Titan and can reach +7.9 at a near perihelion opposition.

Nemausa asteroid (8-09-2008)

Nemausa is a large G-type main  belt asteroid.

Taken from Wikipedia:

G-type asteroids are a relatively uncommon type of carbonaceous asteroid. The most notable asteroid in this class is 1 Ceres. These asteroids are generally similar to the C-type objects, but containing a strong ultraviolet absorption feature below 0.5 ?m. An absorption feature around 0.7 ?m may also be present, which is indicative of phyllosilicate minerals such as clays or mica. In the SMASS classification the G-type corresponds to the Cgh and Cg types, depending on the presence or absence (respectively) of the absorption feature at 0.7 ?m. The G-type, C-type and some rare types are sometimes collected together into a wider C-group of carbonaceous asteroids.

Thetis Asteroid (8/8/2008)

Taken from Wikipedia:

Thetis  is a large Main belt asteroid. It is a S-type asteroid, therefore giving it a relatively bright silicate surface.
S-types are moderately bright (with an albedo of 0.10 to 0.22) and consist mainly of iron- and magnesium-silicates. They are dominant in the inner main belt within 2.2 AU, common in the central belt within about 3 AU, but become rare further out. The largest is 15 Eunomia (about 330 km wide across its longest dimension), with the next largest members by diameter being 3 Juno, 29 Amphitrite, 532 Herculina and 7 Iris. These largest S-types are visible in 10x50 binoculars at most oppositions; the brightest, 7 Iris, can occasionally become brighter than +7.0, which is a higher magnitude than any asteroid except the unusually reflective 4 Vesta. Their spectrum has a moderately steep slope at wavelengths shorter than 0.7 µm, and has moderate to weak absorption features around 1 µm and 2 µm. The 1 µm absorption is indicative of the presence of silicates (stony minerals). Often there is also a broad but shallow absorption feature centered near 0.63 µm. The composition of these asteroids is similar to a variety of stony meteorites which share similar spectral characteristics.

Rhodope asteroid (8/9/2008)

From Wikipedia:

Rhodope is a very dark main belt asteroid, a member of the Adeona family of asteroids. The Adeona family is an asteroid family that formed from the parent body 145 Adeona.

Juno asteroid (8/19/2008)

From Wikipedia:

Juno is one of the largest asteroids, containing about 1.0% the mass of the entire asteroid belt. In a ranking by size, it is tenth. It vies with 15 Eunomia for the honour of being the largest of the stony S-type asteroids, although the newest estimates put Juno in second place.

Amongst S-types it is unusually reflective, which may be indicative of different surface properties. This high reflectivity explains its relatively high apparent magnitude for a small object not near the inner edge of the asteroid belt. Juno can reach +7.5 at a favourable opposition, which is brighter than Neptune or Titan, and explains it discovery predating the larger asteroids Hygiea, Europa, Davida and Interamnia. At most oppositions, however, Juno reaches around +8.7^[9]—only just visible with binoculars—and at smaller elongations a 3-inch (76 mm) telescope will be required to resolve it.^[10] It is the main body in the Juno family.

36 X 60 sec exposures
RCX400 10 inch telescope
AO-8
SBIG ST2000XCM

Virginia asteroid (9/26/2008)

Virginia is a very large main belt asteroid.

30 X 1 min exposures. SBIG ST2000XCM CCD.
RCX400 10 inch telescope.
AO-8 adaptive optics.

The asteroid, named 216 Kleopatra, is a large object in the main asteroid belt between Mars and Jupiter; it measures about 135 miles (217 kilometers) long and about 58 miles (94 kilometers) wide. Recent radar imaging (above) showed a metallic, dog bone-shaped rock the size of New Jersey, an apparent leftover from an ancient, violent cosmic collision.

60 one min images and analyzed four of these in Visual Pinpoint.
RCX400 10 inch telescope, ST2000XCM CCD, AO8 adaptive optics.

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