Nothing can beat a good clock source and converters for sharply defining location, IMHO. When you have that, you don't really need much beyond pan, EQ and verb, IMHO.
But if you want to play around with quasi-3D stuff without spending a few grand to tighten up your source tracks first, this plug can be kinda neat:
http://wavearts.com/products/plugins/panorama/. Some of the very fanciest effects really only work best in headphones, but you can achieve some nice results with this if you treat it with respect.
G.