PayPal is offering a $15 rebate on any single purchase of $30 or more between February 8 and March 31. Valid anywhere PayPal is accepted in the U.S. and Canada, including eBay. You must register your primary e-mail here first.
I always buy my dog’s flea medication from eBay anyways (cheapest price I could find), so it works out great for me. Thanks Tom for the tip.
Added: The page has changed since I first posted this. It appears now to be only open for certain people. For a while, it was available to everyone and even on the front page of PayPal. Bummer.