Did you know that Relay.fm has a store? In addition to some very cool network T-Shirts and buttons they also sell stickers for all their shows, including Mac Power Users stickers!
You can buy a 10-pack of stickers featuring "all the great shows" for $10 or an individual sticker of your favorite show(s) for $2.00 each. I picked up a T-Shirt and some MPU stickers myself.
Also, did you know Clockwise is also selling their own shirt on Teespring right now? You should check it out.
Speaking of t-shirts, I've had several people ask about our plans for MPU t-shirts, especially since we have this fancy new logo. The short answer is yes, we plan to do them but we don't have a specific timeframe. We've had a lot on our plate recently and need to take a minute to catch our breath. But yes, shirts are on our radar!