The Japanese designer+hardware hacking collective EXONEMO just started an ubergeek online service that let you input your own text and create your very own captcha T-shirt!

 Finally I can defend myself from real life spammers!!

A CAPTCHA or Captcha is a type of challenge-response test used in computing to ensure that the response is not generated by a computer. The process usually involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because other computers are unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human.  The term (based upon the word capture) was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper (all of Carnegie Mellon University), and John Langford (then of IBM). It is a contrived acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart."  Currently, CAPTCHA creators recommend use of reCAPTCHA as the official implementation