I started writing this post before my earlier Justice Clothing post, thus the out-of-order title. But underwear is a good place to start the day.
There is an interesting forum discussion that lays out the players in Sweatshop-free underwear thread (Vegan Represent) that's worth going to. I've bough boxer-briefs from (and made for) Union House, and shall buy undershirts from Justice Clothing. This site, from the manufacturer, Lifewear, Inc., won't sell direct to you but will outline how they treat their staff.