Ok, there are lots of cool applications associated with Twitter but one of the coolest I have ever seen is the new one out from Walter Higgins at Sxoop Technologies, makers of the excellent Pixenate imaging app.
How about custom-made T-Shirts which print out a mosaic of images of your Twitter followers or friends? Or even a mug? Or even a shopping bag!
It really doesn’t get more zeitgeisty than that. Enjoy.