Donate to charity while you shop online

Leila sent me this link, and I think it's a pretty cool idea. I know that other people do it as well, but it's nice to have resources right?

I'm partial to the NRDC, but you can choose your own favorite charity and give while you get!

I haven't used this yet, so if you've got feedback, please post it here as I'm interested to here more from people who've used it.