I took the opportunity to volunteer at NECC last year and I am already planning to volunteer at ISTE 2010 this year. Not only do you get a totally awesome t-shirt (free stuff is always cool) but you get an opportunity to help out a great organization and make a few friends along the way. They have lots of opportunities for volunteers including things like putting papers out on chairs or being a "ask me" person that answers questions and helps conference attendees find the right direction to walk!
I'd highly recommend getting involved. It is a great opportunity to help an awesome organization. Sign up on the ISTE 2010 Conference website.