This is the Trikke (pronounced trike). I like how the rider can move forward without stepping off the vehicle. Rhythmic weight transfer from one leg to another is the key to propelling it.
This is a video of trikke riding on urban terrain.
After the success of the land trikke they brought out the trikke ski for people that like the snow.
This is the Rip-stick. Its a modified skateboard. It uses 2 casters and a pivoting connection in the center of the board.
In this video you can see how the rider uses a carving technique to move forward. The creator took the idea from a skateboarding move called the tic-tac. Its pretty much a basic maneuver to get you rolling forward (usually at a slow speed). Ive seen some people riding around the city but hadnt seen people doing tricks on them untill this video. >
http://www.youtube.com/watch?v=cT5a1hMIOVg
People can develop there own style of riding a create their own tricks on them. However, they arnt very versatile and have attract a younger generation of riders. Trikke on the other hand has proved to be quite versatile and seems to have created a cult following. The riders enjoy the freedom of standing up and the carving motion keeps the rider engaged at all times.