Well, seems stupid, but it's not (for now).
So, what about if you are raytracing a 128x128 grid, and then in 512x512 screen buffer draw this 128x128 grid of 128x128x2 textured & colored 2D triangles.
For example, you can shoot rays through every vertex and receiv some U, V texture info where it's shot (assuming that 4 neighbour rays are shooting one and same texture).
If they are not shooting one and same, there can be done something about this (sorry for my english).
SO ANY IDEAS, or PROJECTS on the NET...
I don't care about API - OpenGL, Glide, D3D, RAVE or DRI - just to see some implementation