I'm not as interested in the Olympics this year, but I'll try to catch some events online or something. I've always enjoyed gymnastics - incredible feats of strength. And as boring as it may sound, the long distance races are my favorites because of my own running history.
Tennis, also. I always love tennis. Watching Federer play tennis is one of the amazing things in this world. And not to rehash the earlier discussion, but I'm less interested in rooting for countries and more in just seeing great performances and competition.