Hmmm. How about a very long game... like Morrowind or whatever else is in it's series next? If I'm not mistaken, didn't those games have like... 120 hours of gameplay if you did close to everything in it? Not sure if it's your forte. Aside from that, you may consider getting a model of some kind -- I seriously lose time when I start building models -- I once woke up in the morning with one of the Perfect Grade Gundam models (I'm a Gundam nerd, duh), and it was 3AM when I had finished getting the frame and most of the armor attached. Also, if you haven't done it in a while, it can bring back nostalgia too.
And there's also always the classic book-reading. Pick up a good long-winded series... Ender's Game/Shadow series, or Harry Potter, or whatever. There are plenty of them out there... I dunno, just a few ideas.
--Terin