I recently added distance sensing ability to a Yost Engineering BugBrain that I built a few years ago. I wanted it to have some sort of vision capability so I added a Sharp GP2Y0A21YK ir distance sensor. It was pretty easy to add, just six solder points. All you have to do is connect power, ground, and and I/O pin which I connected to the expansion connector. I used the built in BasicX getADC() function to find the voltage output by the detector. The ir detector outputs a voltage between around 0.5-2.5V which corresponds to distances between 10cm and 80cm. I used the graph from the data sheet to make a look-up table which I use to compare the voltage and find the distance. This works pretty well and now my BugBrain walks around, "sees" objects, and avoids them. I've got some pics but I'm a noob to posting here (although I've been reading for quite a while) so I can't post the project yet. I've got a really sweet project coming up that I'd like to post. It's my Senior Project for school (Shawnee State University) but I'll post more on that later.