Ray Tracing

Goddamn all of these homework threads. Let's talk about something interesting.

I'm starting work on a ray-tracer for shits, /proggles/ Any tips on speed improvements? It's being written in C.
I know the show stopper (usually) is having to check each element in the scene and see if it has been intersected by a casted ray. Any ideas on improvements in that area?

Use the powah of OpenCL and Cuda. It already was done though and decided that it's not feasable yet. So listen >>4 and use every core your i7 can offer.