I have had great fun with the Asteroid Orbital Elements Database. Here is a plot of the main belt and Trojans:
Plotting the size of the orbit and eccentricity shows the various asteroid families and gaps due to gravitational resonances:
There are families in terms of inclination too, of course. Plotting inclination vs eccentricity with distance as color gives this image:
Posted by Anders3 at May 11, 2011 05:07 PM