Well, here's all of BBC's Radio 1's Essential Mixes since 1993: <a href="http://soundcloud.com/das-boy/sets/essential-mix/" rel="nofollow">http://soundcloud.com/das-boy/sets/essential-mix/</a><p>Pretty huge. As far as hacking goes, you can't really beat a 1-2 hour long seamless mix.
Infected Mushroom - Converting Vegetarians<p>Anything by DJ Decryption, he does intellectual rap that's interesting to listen to.<p>Pink Floyd, specifically the Gilmour stuff.
The Field - From Here We Go To Sublime<p>Minimal electronic album that places you into a rhythmic trance, yet doesn't distract your attention away from the task at hand.
It All Falls Apart - The Sight Below.<p>Skulltaste - Mux Mool.<p>World Class Listening Problem - Don Caballero.<p>Hitman soundtracks by Jasper Kyd.<p>I came across The Sight Below and Mux Mool from the excellent ISO50 blog. Browsing for music through the site can be a real time-sink but you'll definitely find something new. <a href="http://blog.iso50.com/category/music/" rel="nofollow">http://blog.iso50.com/category/music/</a>
I'll throw in some soundtracks: Deus Ex (thanks @_danilo), Machinarium, and The Social Network (and Reznor/Ross's new tunes for Girl With The Dragon Tattoo...and Ghosts).<p>and for some other instrumentals: Andrew Bird's <i>Useless Creatures</i>, any non-vocal track by Broken Social Scene, Nosaj Thing (anything he makes, really), and James Blake.