Amazon.com is offering a $2 MP3 credit as a "give MP3s to a friend" type of promotion but you can just apply the code to your account without gifting it. Go to an MP3 page and enter code VDAYMP3S. Click here to go to the Amazon.com MP3 Code Redemption Link
Here are the instructions and TOCs from the promo page.
Happy Valentine's Day! Through February 14, send any MP3s to your friends and loved ones, and get $2 off with code VDAYMP3S. Then share the love with a note about this discount and the music you chose on Facebook or Twitter. Restrictions apply--see Instructions and the Terms and Conditions below.
1. Browse for music at Amazon MP3. All Amazon MP3 downloads play on virtually any MP3 device, including the iPod®.
2. Find the MP3 album or song you want to give. Click the "Give album or song as a gift" button (or the "Give song as a gift" button).
3. Follow the instructions to personalize your MP3 gift and click the "Proceed to Checkout" button. (If you do not currently have a credit card and billing address associated with your account, you will need to add them.)
4. On the checkout page, enter code VDAYMP3S in the box labeled "Have any gift cards, gift certificates, or promotional claim codes?" and click the "Apply" button. Your $2 credit will be added. If you receive an error, make sure you've entered the code correctly and that the promotion is still valid and has not expired.
5. After you've entered the code, click on the "Give song as a gift" button. On the Thank You page, if you like, you can click the Facebook or Twitter buttons to tell your friends about the MP3 you chose and pass the word along about this offer. See how.
Need help? Contact Customer Service via Amazon MP3 Support.
Terms and Conditions:
Promotional offer valid for a limited time only and subject to change. Promotional offer is valid from February 7, 2011, at 12:01 a.m. Pacific time, through February 14, 2011, at 11:59 p.m. Pacific time. You must redeem the code by February 14, 2011, at 11:59 p.m. Pacific time.
Amazon MP3 promotion codes can only be used for Amazon MP3 music downloads and are not redeemable for any other types of merchandise sold at Amazon.com.
Promotional offer limited to one Amazon MP3 promotional credit per customer.
We reserve the right, in our sole discretion, to terminate or modify this promotion.
Offer is not transferable, not exchangeable, and not redeemable for cash, and is void where prohibited by law.