Collision Detection

Can anyone point me to a good site, or offer some help with collision detection in 3d space (using either orthographic or perspective projection)?

Thanks

I learned how to do this on www.flipcode.com.
There is this “Portal Engine Collumn”, take a look at issue 7 (hope thats right).

Tim

Check out gamasutra, as there are excellent articles on that.
http://www.gamasutra.com/