The Aeronix Zipit is an Instant Messenger client. It hooks up with AIM, Yahoo, and MSN, and you can chat with people just as if you were using your compter.
The difference is that you don’t have to tie up your computer with IM. It also starts up almost instantly, so you can just turn it on, log in, and away you go.
It uses wireless networking, just like a wireless laptop. But if you have that at home already, you’re good to go.
They plan soon to make it stream music from another computer on the network as well. That gives you a nice portable jukbox for the house.
And it’s only $100. There’s an excellent article here.