CafePress is a way of setting up an online store for logo-imprinted merchandise very fast and for free. You can upload your own graphics and then just pick which products you want them printed on. (They also package custom music and data CDs.) They print everything on demand and host the online store for you and then you just say how much to mark up each item. You get to keep the profit as they sell the merchandise.
For an example of how quick this is, I set up this store in 15 minutes to sell gear displaying the logo of my team:
The only major limitation of their otherwise great service is that you can only print on white or light-colored fabrics. But hey, where else can you get a thong with your robot team logo on it?