A new website called Ultrinsic is now allowing to put their money where their report card is, speculating on what grade they will get in a class. The higher the grade you get, the more money you can make. (Where was this company when I was in college?)
Apparently, it is totally legal because it involves only skill, not chance (I guess unless you get stuck with the wrong professor).
You can even buy insurance against failing a class and bet that you will graduate with a 4.0 grade point average, at 100 to 1 odds.
It may be worth going to college, just so you can speculate on your grades.