LivingSocial offers a $5.00 donation that is matched 100%
Gap, Inc. (which includes Banana Republic, Old Navy, and Piperlime) is also offering matching donations to anyone who gives through their GlobalGiving campaign.
But the best one I've seen is Forever21. They're donationg 100% of the proceeds for online purchases (TODAY ONLY) to the disaster relief. So go get yourself some new clothes for a good cause! I'd been scoping out a cute jumpsuit at H&M for a few weeks now, (going to visit when I'm nearby, you know, things that sane people do) and I decided my money would be better suited to go to this cause.
Please donate if you can, it's money not gone to waste.