I see silkscreened T-shirts as one of the greatest creations (apparel-wise) of the past 20 or so years. Not only have these screen-printed shirts allowed smaller and less known artists become more popular, they have also made many artists hipper (if not more famous). Stores like Threadless sell cheap shirts with fantastic prints on them, while other artists, like Stacks sell shirts for a higher price, in hopes that the consumer knows he or she is not only paying for art, but also for prestige.
I really like this new company, called Option-G because they make good shirts.
T-shirts have not always been so popular. Although I am no expert on it, I know that the importance of T-shirts has greatly been altered. When they were originally created, T-shirts were what men wore as underwear. Then, T-shirts began to not only be seen as an undergarment, but also as a simple and easy top for boys and girls. Businessmen in the 50s, for example, rarely wore T-shirts when off duty (I think -- I have no data to back this up with ... ), and we're not talking A-shirts here ...
But for some reason, in the 80s, T-shirts began to be seen as a medium for displaying coolness. T-Shirts were blank slates, waiting to be written on. But still, it seemed that T-shirts were for kids and teenagers, not really for adults.
I now am able to judge the coolness of a certain type of Gen Xer (and various other younger generations) by the coolness of his or her T-shirt. This does not apply to all, of course, as coolness does not always go hand-in-hand with graphic design (John Stewart, for example, although not a Gen Xer, is a cool person, but he does not wear T-shirts). The Giant Robot guys are excellent examples of this phenomina. Although I am sure that many of the employees at Giant Robot are over the [traditionally uncool] age of 35, they maintain uber-cool status by wearing uber-cool shirts.
**This post was supposed to just be a plug for Option-G shirts, but it didn't turn out that way ... **