I'm surprised no one has mentioned this, but Garage Games has released their Torque Constructor package (finally) for free.
http://www.garagegames.com/products/torque/constructor/
I've played with it a little and it isn't too bad for creating pieces for Torque maps. It definitely has a lot further to go (if they continue with it) and I'd still prefer they just release exporters for popular 3D programs (to export as dif), but this will suffice for now.