I've found that once the minute details are examined, just about any sport can be appreciated. I'm a member of the sports medicine staff at my local University, and have consequently been exposed to many sports I previously thought were boring/silly but now can begin to see the brilliance behind each of them.
For instance, I used to be bored out of my mind by soccer (football to the rest of the world), but after a few months of constantly watching it, I found myself realizing how the ball was being played around the field, how defenses were baited, how formation shifts were necessary, and why the team that started 6(!) midfielders who were all studs created match-up problems from hell for our home team.
Baseball, volleyball, tennis, wrestling... they all have their own charm to them and I think anyone can appreciate them given enough time.
That said, I have a special place in my heart for American football. It still amazes me how simple and complex it can be at the same time, and I'll go out of my way to defend it against a non-believer.