hello fellow illini audioholics! I am a CS major, graduating in may 2004.
Krannert is definitely very cool. Faculty performances are a dirt cheap $2, and many times there are master classes that are open to the public. Quite coincidentally (or not), I will be going to Krannert tomorrow evening for La Pasion Segun san Marcos, and also this saturday to see Ian Hobson, one of the piano professors on campus.
If you really like it, you can join KCSA (Krannert Center Student Association) and usher shows. After a semester or two of ushering, you pretty much get to choose the shows you want to see to usher. It's pretty cool, I was in KCSA's marketing department my freshment year.