After seeing David Kelley at MIX 08 with T-Shirts on with his website URL on the back, I decided that for DevTeach Montreal, and MIX 09, I was going to do some of that.
I searched around and apparently didn't ask everyone because Bill Reiss told me after the fact that he also used zazzle.
zazzle.com is +1!
I ordered 3 shirts on Saturday November 1, and they were delivered yesterday, Thursday November 6! ... wow...
Not only that, but they look great,and are pre-shrunk 100% cotton good quality shirts.
I'm impressed, and will use them again -- thanks zazzle!