http://www.househacker.com/ househacker/tags/weeds
Use this lightweight burner to clear weeds and their roots in driveways or walkways in summer, or to melt dangerous ice patches in winter. Adjustable regulator valve lets you control flame intensity. Durable, nickel-plated steel and brass burner uses widely available standard 14 oz. propane tank (not included).

These aren't new though: here's a heavier duty unit and a video demonstration of another one in action (although not on weeds, but whatever - you get the idea).

Would it safe to say that people that use these probably aren't the same people that sit on these?

Weed Burner at Amazon.com

Via Toolspotting]]> http://www.househacker.com/permanent/eXtreme-Gardening-via-Weed-Burners