Get the hell away from a computer. Heh, that sounds negative. I love by job but I find it easiest to keep balanced by getting away as much as I can for the weekends. For me, that's hiking, climbing, and back-country skiing. I pay for managed hosting for a reason.

Or work on code of a more interesting variety. As a startup founder, there's usually an interesting problem percolating in the back of my mind, and some days just finding a nice coffee shop and working on code with less distractions is perfect.