I've often said that I don't have an addictive personality, that I don't get addicted to things, even when I wish I would get addicted to them (positive things, of course). But over the last year or so, I've been rather addicted to editing Wikipedia. My watchlist (a list of article that I "watch" for changes) has grown, and I've made more and more edits each month: in total, I've made 3000 mainspace edits and almost 4000 edits in total.
I've decided to stop. I haven't made an edit in over a week. I immediately started using the time for other things, and I feel better already.
I like Wikipedia. I like it a lot. I like it as a great human experiment, and the experiment is working well in many respects. There is much good information on Wikipedia, and many good people working on it. Contributing to it gave me the feeling that I was helpful, helping to create something that other people would find useful, and this is one of my favorite feelings. The addictive aspect came from the fact that there is always something to do on Wikipedia: in less than 5 minutes (even less with practice...), anyone can find something to fix on Wikipedia, so I could get that "helpful" fix any time.