Does the T-shirt approach work? I've wondered what would happen if I put my details on my laptop skin, as I work from a lot of SF/Valley coffee shops :)
I have bought large numbers of T-shirts and give them away as well as wearing them myself. I honestly don't have any statistical evidence that shows they have worked to gain me more business. However I always wear these when going somewhere that I specifically intend to network. In the same way as having business cards does; company branded T-shirts lend credibility to your business and I have been approached and directly asked questions about my business from wearing the shirts.
And believe me; I totally understand the uncomfortable at introducing yourself point. I am an introvert by nature. I have a rule for myself when I go to these places; I force myself to do a minimum of 2 new introductions each time. More is better, but a minimum of 2.