The rhythm game looks like it'll work in flash. It's tentatively called MEWER, although I haven't figured out what this will be an acronym for.
Right now I'd like to check that it works on a wide range of computers. I, of course, don't have a wide range of computers myself, so I therefore turn to the internets for help. If you wouldn't mind spending two minutes, please test the rhythm test.
Score: I'm a cellist, so I consistently get above 95%. If you're a singer, you're probably lucky to get above 50%. :P Other instruments will fall somewhere in between those. (singers: go ahead and try to prove me wrong by posting your scores on my blog. It will be good practice for when I put the real exercises on MEWER. These two exercises are from levels 1 and 3 out of 10.)
Update: MEWER for flash 7.