For their 15th birthday, Ebates is offering 15% off at more than 250 merchants. You can check out the long list here and you might find something interesting. Kohl’s might be interesting with 15% back for one day. Groupon is also at 15%, when the usual highest rate is 10%. You’ll probably notice eBay at 15% as well, but it’s only for Baby and Pottery & Glass categories.
I haven’t really looked at the whole list yet, so if you notice any great opportunities let me know. I’ll update the post if I find anything myself.
If you don’t have an Ebates account, you can sign up with my link (or anybody else’s) and you’ll receive a $10 sign up bonus.
Big Habitat has a nice detailed example on how you can get half off on HP purchases.