Infrared object detector.
Dagu now stocks this IR detector. It has an adjustable range from 3cm to 80cm and a dgital output with indicating LED. Although it can't be used to measure distance it can be used as a cheap alternative to an Ultrasonic or Sharp IR sensor if you just want basic object advoidance navigation. See a video of it in action here.
Max Curent: 100 mA
Range: 30mm - 800mm
The lead has 3 connections. Red is +5V, Green is ground and Yellow is the digital output.