I had some limited success with a 10 hours noprocrast timeout. It broke the addiction, at least, so I only check in the morning and night now. You're right though, you really need to find something to replace old procrastination habits with, otherwise you'll just pick up new ones.

http://news.ycombinator.com/item?id=114401

I've certainly started visiting Programming Reddit more since visiting news.YC less. OTOH, I don't think it makes up for the full difference, and my startup has gotten the balance of that time. That could be because the startup is more mature and hence more fun to work on now, though.

I had the crazy idea (since my startup is all about casual games) that instead of blocking people from playing games all day, you should just turn their daily work into a game. Carrot, instead of stick. Don't really know how the specifics would work, but it's something I'd like to play with as our game-creation software gets more mature.