This is a nice fat wheel for making a mars rover type looking vehicle ... the hub ties to a servo motor/servo horn or up to 6mm motor axel.
This is another of many entries to the makezine.com/go/makerbot contest ...
blog.makezine.com/archive/2010/04/makerbot_giveaway.html
I really need a job ... but I can design a custom part if you like on contract.