I think you should go with the classic "Property of -----" shirts that were prevalent in the 80's. You could put a cabinet sillouette (sp?) in the middle. Simple yet classic. people don't need to know what it means, but the shirt will make them ask - you could even put the website underneath. i order these kind of shirts all the time for my sports programs (I'm an athletic director). They are very cheap if bought in bulk.
check out
http://www.giantsportsfactory.comYou can design online!
JT