I used to play a lot in high school and early college. Yahoo Chess online. Got my ranking up to about 1800 (which was pretty good on their ladder system) but then lost to some real scrubs, ranking went down to like 1550, and lost interest.
I still play once in a while. The school where I work has a chess club, and although I'm not the faculty advisor, I still go sometimes to play with some of the kids. Pretty fun, but I'm not as good as I used to be.