One of the things that I found very useful at ISTE11 was making personal connections with vendors. I was able to get tips, ideas, and even some great free resources from them. I also learned about discounts and grants to help with the purchase of some of the products. In the future, if I need assistance with something, I now have a contact that knows me and that can be a great help.
Some of the vendors ran some very good sessions on how to use their products in the classroom. Mimio, Google, and HP had some great ideas and resources. Many of the vendors also use teachers to present these sessions. These are teachers who actually use the product in the classroom, not some PR person. These were very helpful.
I really think that spending time with the vendors is important to make connections and learn more things. Especially if you are already a customer of that company. It is also a great way to evaluate a product before investing any time or money into it.
The vendors also help keep the costs of the conferences down, so visiting them keeps them coming back.
We returned with two huge bags full of free swag (posters, pens, post-its, etc.) and materials to review about the products and services. A few vendors also offer free trials of their products to people who were there, that they don't offer to anyone else.
The vendor exposition was a very informative and useful part of the conference.