Evapo Rust
 

I bought some of this stuff recently and so far it seems to work very well! Most of the things I have used it on are not heavily rusted, though. Light rust takes a couple of hours, heavier rust takes overnight. I don't know how practical it would be for large parts, but for smaller ones it does a good job.
I also tried it on a small area on the door on my truck. I soaked a cottonball in the stuff then put it on the rusted area and covered it with saran wrap and taped it to the door, a couple of hours later and no rust. It affected the paint a little, but I just waxed the area where the stuff contacted the paint, and it looked normal(BUT, my paint is original and not in GREAT shape-so be careful if you use it on your truck). The evapo rust is also reuseable, non toxic and environmentally friendly(according to the Mnfgr.)

http://www.orisonmarketing.com/corro...vapo-rust.html
I've got pics at home of an old C-clamp I tested this stuff on and I will try and remember to post them later.
Mike:flag:

Before

After.
No rubbing or scrubbing. The clamp apparently had black paint on it at one time, and some of it is still visible, but the evapo rust didn't remove it.

Eastwood Oxi-Solve is similar. I bought a gallon jug of it in 1990, and the stuff still works!