Soma FM is one of my favourite things. Their stations are among my top listening while working. The lack of ads/interruption and excellently compiled playlists make for wonderful listening that truly augments my mood and ability to concentrate.
(I just hope that my link won't DDOS it)
[0] http://bluemars.org/ [1] http://echoesofbluemars.org/index.php
* (mandatory, already seen multiple times on HN) http://musicforprogramming.net/
* Kruder & Dorfmeister - The K+D Sessions. Fantastic mix.
* Apparat - The whole discography, but especially Silizium, and Krieg und Frieden. Both mix deliciously electronic and violin/cello.
http://ambientsleepingpill.com/ and the classic http://www.sleepbot.com/ambience/broadcast/
Subdued, but steady beats to maintain pace, with a touch of atmospheric electronics.