Link: www.musictheory.net

This interactive site offers music theory tutorials, ear trainers, and other misc resources in a clear, helpful manner.  I found this site extremely helpful when I was taking 4 semesters of Aural Comprehension during my Freshman and Sophomore years.  I’d recommend it to anyone wishing to increase their ear training skills.  I still visit it every now and then to brush up on my skills.   

This is a great site for students of all ages, because many of the trainers are adjustable.  For example, there is a trainer for practicing key signatures.  If you go into “Settings,” you can choose exactly which key signatures you wish to be quizzed on, and leave the others unselected.  

What a great resource for music teachers and students!