i know an interesting (but not very common) application for volume textures. you can load the frames of a video into a cube and then watch it from the other sides (for example left to right instead of the intended front to back). this leads to extremely interesting effects as it swaps the time and space axis of the video. laugh (i experimented with something like that many years ago but it wasn't realtime. with a volume texture you could easily make it realtime.)