To all those suggesting an instrument,
I do already play the piano (and have for many years) - for some reason it isn't really the outlet for me, nor am I that keen to pick up another instrument. Funny, because I love listening to music. Maybe it just isn't my outlet. Your mileage may vary.
Sports, on the other hand, are very much a part of my next-year-plan, but since I already play the sports I want to play (I just need to have more time to play them), I don't really need any suggestions, although I appreciate the effort. (And I also agree that for those who don't play a sport, getting one is great for your state of mind as well as your physique.)
And c'mon GAF, surely there are even more great resources out there that are essential to this thread!