Not a charity, but a cool place to get stuff. And hum 'look for the union label' as you do so.

Variation on a theme: http://www.powellsunion.com/ - if you don't have a local bookstore to support (and you should), or you're shopping for someone not local to you, 10% of all sales made through the ILWU Local 5 portal goes directly to Powell's employees through their groundbreaking profit-sharing agreement.