Artists include a range of up-and-comers including The 88, Dealership, Kutless and Semi-Precious Weapons.
The catch is that they'll only be available for Rock Band 2 owners.
The tracks will be downloadable by using the DLC redemption code in Rock Band 2's retail packaging.
According to Harmonix, Rock Band's online music store has exceeded 25 million paid downloads.
Rock band 2 shipped with over 80 on-disc tunes.
The list of upcoming free songs is below:
The 88 “Sons and Daughters”
Authority Zero “No Regrets”
Between the Buried and Me “Prequel To The Sequel”
The Cab “Bounce”
The Chevelles “Get It On”
The Cocktail Slippers “Give It To Me”
Dealership “Database Corrupted”
Endeverafter “I Wanna Be Your Man”
The Ghost Hounds “Ashes To Fire”
Hollywood Undead “Young”
Kutless “The Feeling”
The Len Price 3 “If I Ain’t Got You”
Lesley Roy “I’m Gone, I’m Going”
Opiate for the Masses “Burn You Down”
Semi-Precious Weapons “Magnetic Baby”
Shaimus “Like a Fool”
Thenewno2 “Crazy Tuesday”
Tickle Me Pink “The Time Is Wrong”
Underoath “Desperate Times, Desperate Measures”
X Japan “I.V.”