I agree they are a little annoying... but damn! Those things look like fun! I think the kids call them wheelies.
Have you seen this contraption...
http://www.skipro.com/detail.aspx?ID=472&gclid=CNCk2ov6pIsCFQlaPgodancqkg the wave board??? Kinda like a skate board but with only one wheel in the front and back that spins completely around on an angle. Talk about a lawsuit waiting to happen. One of my friends kids had one, he could go UP the hill riding it.