You can now create codes (like “ukulele” or “snooki”) that your fans enter at checkout to receive a discount on your music. Discount codes can be valid for anything on your site, or just a specific track, album or package. You can make a code expire on a certain date, or let it remain valid forever. And you can see how many times a given code has been redeemed, so that you can create different codes for different channels in a marketing campaign (YouTube, Twitter, email, etc.) and easily track their effectiveness. All of this is set up from your Tools page, like this:
and fans enter the discount code in the checkout dialog, like this:
Note that you cannot create a discount code for 100% off (essentially, a multi-use download code). We may add that in the future, but no ETA just yet.
UPDATE December 14, 2012: We now support discount codes on all items with prices above zero, including items where you selected “let fans pay more if they want.” In that case the discount simply reduces the minimum price.