I stumbled upon this website (www.reactee.com) again and was reminded of what a fantastic one-to-one interactive marketing opportunity this is.  I love the fact that it gets attention, creates a reaction, and as marketers we can deliver a highly relevant message back.  Think about the possibilities for this in event marketing. 

Hand out tradeshow-specific shirts and deliver a custom message with an invite to visit a website, check out your blog, follow you on Twitter, or sign up for a webinar or case study download.  These would be great for street teams wanting to create a viral  marketing movement.  Imagine outfitting retail store employees with these shirts.  Text a code, receive a coupon on the spot.  Take your phone to the cash register to redeem it.

In a world where people look at what you wear, t-shirts have for a long time been used as a communication channel.  The problem is that message couldn't change.  Now it can.  I really like the possibilities with this.