I had never heard of this before, the threadless ballscrew that basically uses bearings at an offset to move up and down a rod. It looks like a good solution for things with a known weight/load on them. But I started digging some more and it sounds like this is a good solution for something that needs a ballpark movement, but not a precision one.
http://www.instructables.com/id/Threadless-Ballscrew-3D-printed/