Body Fat and the Tanita (the most well-known and available brand in North America at least).

A quick search with the Tanita keyword revealed some informative looking posts (hey, if Doreen starts the thread, you KNOW it's a good one ) in General Low Carbing and the General Excercise threads ... as well as many many others.

Enjoy.

PS: Canadian Tire Online is VERY likely to have them if there's no CT in your town.