My absolute favourite album to code to would actually be the Tron Legacy soundtrack by Daft Punk, but I've also spent the last few years at uni listening to http://www.prettylightsmusic.com/ while I code: his albums are all available for free/donation, and the genre is kind of down-tempo electronic. There's the occaisonal vocal sample, but I've found it doesn't distract me from work.
I listen to the Tron Legacy soundtrack a few times a week. It's perfect for getting shit done. Enough intensity to keep me focused, not enough to be distracting.
I'm also partial to Fuck Buttons - Tarot Sport when I want something weirder, and DRMHLLR when I want something less electronic.
The Tron Legacy OST is always fun, but it's even better when you listen to it doing something suitably epic, because many tracks sound so unapologetically grand. Perfect sound track for handing in an important paper and doing mountain climbing. Or doing mock epic things: feel like Batman while chopping onions.
Some of the tracks from the remix album are also pretty cool.
Endtroducing by DJ Shadow is also worth a listen, as although there's vocals, they're generally calm. Example: http://www.youtube.com/watch?v=32X-ieCav-M