I love fantasy sports.
They add a new dimension to watching sports...I have rooting interests in games I wouldn't otherwise care about.
I run baseball and hockey keeper fantasy leagues with a handful of guys...which mainly consist of family and friends I've played hockey with for years. And I run a fantasy football league at work.
If you only participate in one league for each sport, it's easy to maintain. If you have time to check your email each day, you have time to maintain your fantasy team. And football is easy. You really only need to set your lineup once a week, and maybe check it again Sunday morning before most of the games start if you're picky. It's when you start doing more than one league for each sport, that it can be a pain in the ass and actual work to keep up with it.
Fantasy baseball is easy to keep up with. You check your lineup each morning and put in your starters for the day. It usually only takes 2 minutes at most...unless your are making a trade or adding or dropping players, then it takes a few minutes more to decide what you want to do. But not a big deal if you actually enjoy baseball. Same thing with hockey. I'll spend a while analyzing what moves I want to make, because I enjoy it.
Yahoo has pretty good, free leagues.
fleaflicker.com has what looks to be a good fantasy football league, we're trying that one this year.
I'm sure there are lots of other good ones.
I haven't done a pay league, and I don't play for money. It's all about the bragging rights with my friends...and at work we have a trophy that gets passed around. That's good enough.
In baseball and hockey, we hold the draft at my house. It's a good time. (and it will be even better once the new house gets built and we can hold the draft in an actual game room.