Logitech (http://www.logitech.com) has unveiled the US$59.99 Wireless Trackball M570. Compatible with Mac OS X 10.5 and higher, its laser tracking sensor uses the ball, rather than a surface, to guide movement.
Logitech’s newest trackball also has a scroll wheel and back/forward buttons. Plus, it uses the tiny Logitech Unifying wireless receiver. It stays in your laptop, so there’s no need to unplug it when you move around, and the 2.4 GHz wireless means a connection from up to 30 feet away.
You can add a compatible keyboard, number pad or additional mouse to the same receiver so you don’t fill up all your USB ports. You can purportedly go for up to 18 months without replacing the included AA battery.