I've only recently increased the technology level in my classroom. I don't usually believe in technology for technology's sake - if I can teach something just as well with paper and pencil, I prefer the low tech route. In order for me to want to adopt a technology, it needs to present some clear benefits.
I didn't just want this wireless tablet, I craved it. It is about the size of a clipboard, weighs just over a pound, and serves not only as a mouse from anywhere in the room, but allows you draw and write over what is currently displayed on the screen. Put up a problem via powerpoint, and then hand write the solution from the middle of the room. Better yet, hand the tablet to a student and let them do it. Or, you can display student work via the document camera, allow another student to correct or supplement the work (without changing the original), and save the result as a pdf file.
Cost is about $350, and requires a decent amount of technology as infrastructure to support it. Still, i expect that I'll probably get one sometime before christmas break.