While most of the world has settled on either a standard mouse or a touchpad, there are still plenty of designers trying to reinvent the wheel. Personally I prefer the old IBM style pointing stick on my laptop over the more common touchpad, but there are other ways to move your cursor when you don't have a mousing surface. The Optical Ring Mouse is a tiny trackball that you wear under your finger then operate with your thumb. The only problem is that instead of fashioning it into a comfortable ergonomic shape that fits your palm, the designer has gone with a straight sided square.
The optical Ring Mouse is available in the UK for about $30.