Prior to the release of Rock Band 2 Harmonix and MTV Games promised that the 84 tracks that shipped with the game would be bolstered by an additional 20 downloadable songs soon after launch.

Today Harmonix have unveiled a new website that allows those who have purchased Rock Band 2 to sign-up and claim those 20 tracks.  The website will prompt you to enter a redemption code – found on the back of the game’s manual – along with your email address and date of birth.  This service will also be available to PS3 and Wii owners, upon the game’s release on those platforms.

No word yet as to when you’ll actually be able to download the tracks or which songs are included.  Stay tuned for more info.  In the meantime you can check out our Rock Band 2 review here.