This shirt just came out yesterday (and I got one)!
http://www.bustedtees.com/deal/coolweirdal" onclick="window.open(this.href);return false;
They also have this UHF shirt:
http://www.bustedtees.com/uhf" onclick="window.open(this.href);return false;
This site has a bunch of Al shirts that, in my opinion, aren't all that great (but that twine ball bumper sticker tho)...
http://www.zazzle.com/weird+al+gifts" onclick="window.open(this.href);return false;