Me, I build plastic robot models. It's no brain power at all, just precise physical motions. It's mindless and enjoyable, and at the end of the day you have something to show for it.
There's a lot of posts here saying take a break, but you really have to make sure that you are truly taking a break, and not just substituting programming with something else that uses the same parts of your brain.
edit: Here's one of the first models I built. Unpainted just to see what it looks like. http://www.flickr.com/photos/37553996@N07/sets/7215762298535...