Cyberdog, a company that appears to be devoted to progressive clothing and techno music, is selling electonic t-shirts. (To find them, click on "t-shirts" and then "light-tee s/s" or "light vests".) Their designs include one with a 32-character programmable scolling message on the chest and another with a sound-activated graphic equalizer. Unfortunately they only have a picture of the scrolling message tee, though there are animations for the rest. I can't decide if these shirts are cool or goofy. Maybe they're both.
Something I don't hear much about is how you wash this type of clothing. Cyberdog says that each shirt comes with a battery pack and plug in module, the removal of which I would assume makes the shirts washable, but I'm not completely sure about that.
If you visit their site, it's worth taking five minutes to look through the rest of their clothes. A few things interest me, like their long drape skirt, but clearly I am not in their target audience! Still, it's fun for a look.