The Sharp Zaurus SL-860 is nice. It's basically a fully functioning mini linux laptop that fits in your hand. Qwerty keyboard, 640x480 resolution, touch screen, display swivels round etc.
It can take CF wireless network cards, although the battery life goes down to around 1hour when it's connected.
As far as uses goes, it's a good smaller alternative to a fullsize laptop.
They're only officially available in Japan, so if you want to get one you need to buy it through an importer who has converted the software to English. A US based company that does this is
http://www.dynamism.com/zaurus/