I’ve recently been taking part in beta testing the new gDEBugger for MacOSX. A fantastic program that for those who have used GPAD when developing for the PS3, or PIX when developing for the XBox360 will find familiar.
It gives details information about bottlenecks in your rendering, things that may be wrong, state changes that weren’t necessary, etc. And another useful thing, it allows you to view your textures, their mip maps, your frame buffers, and more importantly, depth and stencil buffers.
Today the license I was given expired since it is now out of beta and available to buy, though they were kind enough to give me a promotional code that would give me 15% off when I purchase.
I recommend it to any OpenGL developer, its helped improve my own game engine by showing me flaws in what I was doing.