Dlink DCS-100W (Score 4, Informative)

The Dlink DCS-1000W network camera is a great option for this: the camera is inexpensive (under $300), has a built-in 802.11b connection, uses interchangable standard (CCTV) video lenses, and is robust and reliable. We've used this camera for over a year so that grandparents who live far away could view their granddaugher; the camera has made a real difference, and has performed flawlessly. This page contains some sample images from the camera.

Dlink also makes a model that streams audio in addition to video, the DCS-2100+