Photography too... particularly landscape and wildlife photography. It forces you to get outside, to wait, to be still and patient.

Photography also :) glad to see some photogs on HN. I do mostly street photography - I find that it gets me engaged with people and forces me to be much more social than I'd otherwise be (I do stare at a screen all day for my day job...)

[edit] Also, working in an industrial kitchen. Nothing like getting your hands dirty that takes your mind off brainy matters like programming.

In the end IMHO the best hacker hobbies are the ones that are mentally nothing like hacking at all.

Oh cool.. do you have any of your photos online?

I'm also into street photography: running a photoblog where I post a photo every workday (http://journal.boblycat.org/cosmozoo). Still going strong since 2005 or so, and I concur it's a great compliment to screen-gazing.

Sure do: http://www.flickr.com/photos/potatolicious/

Nice pictures :) I wish I could keep up a shoot rate of one a day... Nothing kills the creative eye quite like code all day ;)