Cafe Press
Best self t-shirt creation website I've seen. I've personally never used it, but my friends have. Price is decent, quality is decent, not sure what they use for getting the images on the shirts, but they seem to be doing pretty well.
What shirt plans do you have. I know it's lame, but I can tell if I'm in a liberal or conservative town/city if I walk down the main street with my local store t-shirt made "I Fuck On The First Date" shirt. Get everything from looks of disgust and turning heads, to people pointing and laughing, and wanting to shake my hand. I've stopped wearing it after bumping into a prostitute with that shirt on (similar to my experience with gypsies in South America, she followed me to my car, and then tried to get in!!!).