Hot on the heels of the game's "Peer Review" DLC, Valve has made available the third and final volume of "Songs to Test By," free of charge (as usual) through the game's official publicity site. There are 24 tracks, including the closing credits theme "Want You Gone," plus another six snippets for ringtones. The Volume 3 .zip file is 141 megabytes.
Soundtrack: Volume 3 [Portal 2]