Bowflex, which we happen to be fans of.
I've been using TreadClimber since around 2005 and I find them to be among the most unique treadmill-style machines currently on the market. I can get my heart rate up very quickly because of the incline/climbing motion, which allows for a quick entry into the optimal "fat burning" zone.
We would love for someone to share there own reviews and opinions of the new WalkTC machines. They seem very cool but they definitely aren't cheap (although there is apparently a new under-$1000 TreadClimber model)... so obviously we'd like some feedback before deciding to invest.
Please leave your questions ad comments below...