I beleive last spring I stumbled across a program that could access texture memory for either OpenGL or DirectX and dump textures to a file so that you could see the textures used in the app. I checked out the sticky threads in this section and I've badly googled for it. Does anyone know of a program that does this?

D3DSpy can let you examine the textures in use by a DirectX application (you have to mask the D3D dll with the D3DSpy dll though). I don't think it can dump them to a file, but it will also let you look at a bunch of other interesting stuff (vertex buffer contents, index buffers, render states, etc.).

I don't know of a similar tool for OpenGL though, sorry.