Shower, fold laundry, play a numbers game on the computer. Anything that is mindless and where I have nothing to do but think. Usually, even if the story has gone silent on me, these sorts of activities perk it up and tell me where to head next.
Also, I don't get blocked often. If it is a bad block, it's because I've messed up in the plot somewhere and need to go figure out what went wrong before my brain will keep moving on. My muse is sneaky like that ;-)