Does anyone know of a good 3D benchmarking program comparable to 3DMark2001 except using OpenGL instead of Direct3D?
Probably any game that has a benchmark utility. After all, benchmarks mean nothing, it's how the graphics card actually runs in an application/game. If the game doesn't have a benchmark, you can use a program called FRAPS. Anyway, pardon my lack of knowledge about the 3DMark series, but doesn't the latest version of 3D mark have a OpenGL benchmark utility?
Most games benchmark DirectX rather then OGL. If i'm not mistaken SiSoft Sandra has a OpenGL bencher and i think even the Norton Passmark thingy has an OGL tester.