hi-liter, sticky note pad for marking the schedule.
Zip-lock bag of nuts/dried fruit & water bottle
Bring lots of the sticky address labels to stick on venders lists and
for new friends. Saves time just pealing and sticking and you know they
can transcribe accurately from a label.
Brookstone (one in most airports) has a strong tiny flashlight the size
of a quarter which can hang on your thumb out of the way until you need
it in the dark rooms. I keep mine in my conference materials and it is
still working on it's 7th year through several conferences each year.