I'm just now growing from the 2D to 3D world and seeing what's out there. This Open source software is mainly for 3D printing, which I am also interested in, but I thought it might be of interest to some of the folks here who play with STLs. I don't, yet (waiting for a software sale on CW's part, hint hint). It's available for Linux, Mac, and windows.

https://github.com/repetier/Repetier-Host

-Jim