I am expecting to see several iPhone applications at NAMM, but this one is particularly handy as I start my tour:

It can be used to map the convention halls, search vendors by name, category and location, and “bookmark” them so you can see on the map where you might actually want to go (and thus avoid getting lost in the endless sea of guitars in the middle of the convention center). I was able to quickly put in some of my own priorities as well as those I have followed on matrixsynth and elsewhere.