Teespring does some really cool work with non-profits, launching kickstarter-esque campaigns for them (at no cost) and giving a cut of the proceeds to that organization. A few friends of mine who run an education non-profit in Philly (http://www.12plus.org/) did it a few months ago [1] and it really helped them out a lot. Coupled with this blog post, TeeSpring seems like good people.
[1] http://teespring.com/12plus