Rock Band 2 bonus registration open, tracks 'in a few weeks'

Harmonix is now accepting redemption codes for the twenty bonus FREE! downloadable tracks that come with the purchase of Rock Band 2. You'll have to give up (or make up?) some somewhat personal information and opt out of marketing spam, but after it's all submitted you should receive a speedy confirmation email locking you into your prize. And then, Harmonix says:

"Sit tight. The Bonus Tracks will be available in a few weeks -- we'll send you an email with a download code and redemption instructions as soon as they're ready." And by the way, we still have no idea what's in this mystery track pack. But it probably ain't some AC/DC. (Update: Here's one possible set list -- thanks phragit!)

[Thanks to everyone who sent this in!]