Many open source projects sell stuff for developers (T-Shirts, caps, etc.) to support development, and show off their skills. I realize that TBB might not be a large enough project for this yet, but I wouldn't mind buying some TBB-wear to show off my TBB-ness and support the project with some cash.
Some day we might have a TBB Swag division to coordinate our promotions with advertising wares (wears?), but I wouldn't hold my breath. We do have a very scant supply of T-shirts, mostly left over from last year's OSCON, that we can make available to interested people as long as supplies last. Reply to this thread and we'll serve as many as we can, in the order they show up here. Don't all reply at once, now. ;-)