I definitely make use of a whiteboard at home and at work. I don't know brand names specifically but at work we tend to have rather large boards (6 feet wide by about 4 feet tall) and they cost several hundred dollars. At home I have a smaller board (4 x 3 feet) that I picked up at my local office supply store for about $30-$40.
I've been told you can use a product called "showerboard" from a local hardware store. It comes in large sheets but I'm not sure how good it is with the markers.
Another option you could use is a piece of glass (ex: in the move "A beautiful mind"). You could paint the glass white on one side. I actually did this on a small scale for a gaming table I built, works very well.
As for uses ... I use my whiteboard at home as a design station for home/side projects, I write reminders to myself and little notes. The whiteboard at work is used primarily as a design studio. When we gather as a team to go over a project we lay our designs out on the whitebaord and we can easily tweak them without going through alot of trouble. When we're all done we take a picture with a digital camera and save/print it.
If you had a "smartboard" you could print whatever you wrote on it but smartboards cost a pretty penny more so they're not practical at home and are only generally affordable by companies of a decent size.