Head over to Amazon's vast MP3 selection and pick out $2 worth of songs you want to download. Look for the “Buy” button underneath the song or album, then click on the Redeem a Gift Card or Promotion Code link. Enter Amazon.com Promo Code VDAYMP3S to get $2 in Amazon credit to your account!
I've been waiting for a little credit to download a few children's songs on my phone. I don't use it for music very often, so it's nice to get the tunes for free!