Performance Profiling of OpenGL Shaders

nVidia PerfWorks can. They also have FX Composer, which includes some profiling with a graphical front-end (but FX Composer is now basically discontinued--you can still download it, but it's no longer being updated).

AMD/ATI's GPUPerfAPI and GPUPerfStudio provide similar capabilities. They also have GPU ShaderAnalyzer to do static analysis, but I believe it's restricted to DirectX shaders, not OpenGL.