mr rebates-Budget 2% back
 

there are others, but thru this site www.mrrebates.com , you can receive rebates and budget is listed for 2%. I have used this for 5k/Garmin fastbreak promo w/Delta and received my miles. The money can go into your ebay account if you have one and are set-up w/paypal. It's a small amount but will certainly add up if you do a lot of rentals during the promos Delata has going on now for up to 8K miles.

Thanks for the heads-up!

Piggybacking on the original post - Upromise offers twice the rebate at 4%.