If you fancy bopping your head to the mechanical tones of Portal 2's music, you can now download Volume two of the official soundtrack for free straight from Valve.
The second of three volumes includes such hits as 'I am not a moron', 'Bring your Daughter to Work Day' and 'You Are Not Part of the Control Group'. Also available are a selection of ringtones for iPhone and Android users.
Valve released volume 1 of the soundtrack, containing 22 songs, back in May. Volume 3, the final part, is apparently 'coming soon'.
Head through the source link to download them both. Legally.