Here's an online test to see if you're tonedeaf. It takes about 6 minutes, and requires a quiet room and a computer with Flash 8 or 9.

The scoring model is as follows:
Greater than 90% correct: World-class musical abilities
Greater than 75% correct: Excellent musical abilities
Greater than 60% correct: Good musical abilities
Less than 50% correct: You may have a pitch perception deficit

My score was 63.9%.

While the test may have its flaws, I think the result was about right. I always considered my musical ear to be pretty good, but not great, which explains why I can play several musical instruments, but can't really sing.

As for the test, it's a series of musical passages that you need to compare and judge "same" or "different." I think singers have the advantage here, because they practice tonal memory in their training, and it's got to get easier over time. Also, the passsages can be quite long, and if the difference is a half-step somewhere in the middle, then the test is more about memory than it is about tonedeafness. Finally, I've always found that I'm better at picking out pitches on instruments I'm familiar with (piano, trumpet, and even a singer's voice). Some of these passages were done in tech/funk MIDI stops that make discerning them harder (although that might just be me, and a valid reason to get a lower score).

Anyway, check it out & report your score here...