you can make a registry through the website with a whole list of national chains (including macy's, amazon, home depot, target, linens n things, etc) for your wedding, and up to 8% of whatever is bought off your registry will be donated to charity, at no extra cost to you or your guests.
It sounds to me like a great way to give back a little of the immense amount of money we spend on our weddings, especially since it really is absolutely no inconvenience to you, as a lot of the stores listed are places you might set up a registry anyway. I was torn between registering at Macy's, Bloomingdales, and Fortunoffs, so now I'll just use the site to register at Macy's and that makes my decision easier, and does something good for the rest of the world.