A terrific tool for training your ears: Mr Soundman

I came across this game earlier today. It is a VSTi that boosts certain frequencies during a particular piano/guitar/drums/string piece. Then you have to select where you think the boost is. Extra points are granted for being closer to the actual freq. One of the best things I have ever come across to train your ear.
 
http://www.v-plugs.com/mr_soundman