Treads available for LDraw
Philo, MCP and relentless Wizard of LDraw parts, has published LDraw files for the treads contained in the NXT Education supplemental kit (other configurations of the treads can be found here and here).
Hence you can model your NXT robots that run on these treads now in LDraw.
Chris, in the Black Forest, the t(h)reads would have been carved of wood.
Thanks for hinting that to me - me German, me no good speak English. ;)
I always make the same mistake when I try to spell that word, so it must be this side of the atlantic... (OK, the channel)