Depends on the place. At work, I usually take a quick break to read web comics, The Onion, or other time-wasters. (High-powered nerf weaponry is on my to-do list.) Sometimes it helps to work on another unrelated problem; if I'm thrashing on a DB issue, I might switch to something graphics-related. Or I can SSH home and play rogue.

At home, I have more options. Playstation 2, idiot box, computer games (rogue is excellent for that sort of thing, since it's fairly brainless and you die quickly), guitar, arseloads of books, a wide selection of pubs within a ten minute walk, whatever. (That reminds me; when I get a decent amp, I should pick up a cheap guitar and set it up with the old amp in my office. Oh. Headphones. Sure.)

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:wq