The Amazon MP3 Store offers downloads of select MP3 albums for $1.99 when you link your Twitter account to the site. (Note that it will also automatically register your account to follow @amazonmp3 and it will tweet about the offer.) With 25 albums available, it yields a number of price lows. (iTunes charges $9.99 for most albums.) The credit can be redeemed on one of 25 qualifying albums from the Amazon MP3 Store including artists such as Gotye, U2, The Postal Service, The Shins, Nirvana, Paramore, and more. Amazon MP3 Downloader is required. Deal ends December 23.

Note that the discounted price will not be reflected at checkout, but in the order confirmation, which will be emailed to you after your purchase.