Portal 2 has been a popular game ever since it came out, though I'm sure many were too busy laughing at some of the dialog or trying to avoid being killed by GlaDOS to notice the music. However, now is your chance to experience some of the music behind Portal 2, as Valve is offering the first of three volumes of the game's soundtrack for free. Valve calls them "downloadable aural stimulus packages" but either way, now you will be able to enjoy some of the music that went into the game. The first volume features 22 tracks, so it isn't exactly small by any means. The first volume (and presumably all) is being called Songs To Test By which is a fitting title. Jonathon Coulton's "Want You Gone" isn't included in the first volume, but perhaps it will appear in either of the next two. Feel free to download the first volume and even some ringtones here.