Not sure if this is targetted only, but I got an email from Half.com for an old account I used to have a long while back that gave me a code for 15% off 1 item at Ebay when I pay with paypal. Code is CEBAYHALF2008. Maybe it will work for someone.
This, like most other ebay coupons, will only be good for the people who actually receive the email from ebay/paypal. And for these lucky people who get it, it's a one-time use coupon. Anyone else you tries to use it, it won't work (unless you got the email yourself but never bothered to look).
I used it today to buy 2 sets of Corsair Dominator DD3 6gb kits and yes it works with cashback. I got the 15% off (limit is 100...it came out to be $97.20 off a purchase of ~$640) and then I got another $162 cashback. RAM came out to be $388 shipped for both kits together. As I said, it is likely targetted...it was sent to an old email that was linked to an old Half.com account I have not used in years. I threw it out there though just in case...YMMV. Smoking deal for me as I got 2 sets of ram for 40% off.