Jet Profiler is a great MySQL profiler. As the world of operating systems is getting more and more mixed, Jet Profiler offers a huge advantage: It is a Java based application and therefore able to run on Windows, Max OS X as well as on Linux.
Most of the time Java based applications tend to be very slow, however Jet Profiler shows that Java based applications can be fast and responsive as well. Even after hours of recording the UI stays responsive. To give you a working example, I had it recording on a server and real world load.