There was a thread on this not too long ago:
http://www.chiefdelphi.com/forums/sh...d.php?t=106808
In that thread I posted MOE's pit design. MOE uses two rolling workbenches that were built in the robot lab by the team over several years. They have two overhead, removable shelving units. Dissassembled, the whole pit can fit in the back of a pickup truck for transport to events. One workbench is shown above. They have a built in vise and I think a drill press.
You can get Autodesk drawings and a ppt presentation on the design at
http://moe365.org/moepit.php