I recently bought a pack of FlexGrip Elite pens (made by PaperMate) at a local Wal*Mart. I bought them (as opposed to any number of other packs of pens) because it came with a free iTunes download. After opening the pens, I pulled out a little card with a code on it. As per the instructions on the card, I went to http://www.papermate.com/songs and entered my email address and the code from the card. Lo and behold, it gave me an iTunes code that can be used to download a song. Cool. Then I hit back on my web browser and entered another email address and changed one of the digits of the original code from the card that came with the pens. To my surprise, I was presented with another iTunes credit. I tried this a few more times and every five or six tried, I would get an iTunes credit. After getting a couple hundred credits, this got boring. Perhaps there is some way to automate this.
Anyway, I am NOT suggesting anyone do what I did, but you might want to buy a pack of pens and get a free iTunes download.