Found some pretty cool thing searching around for pitch testers (I was looking for something to see how high or low something can go in terms of pitch), which is based around a study on some things about sound.
There's a tonedeaf tester, a visual music tester, a rhythm tester and a pitch difference tester, so... well, I found it quite fun, so here:
http://jakemandell.com/tonedeaf/