Distance sensor

just a heads up in regards to my questions ;) I am a flex developer and I have no knowledge of any-sort in regards to hardware sensors... So my question, I would like to receive in a flex app the distance between 2 points could someone tell me what kind of emitter and what kind of receptor should I be looking into... ( I know the question is really vague but I have to start somewhere ) any pointers would be appreciated :)

You could start by telling us the constraints: cost, distance, underwater,indoors. The usual stuff.

ok ;), indoor, the cheapest possible, it doesn't need to be super accurate, a couple of centimeters margin would be tolerable and the max distance would not excess 1 meter

you could look into ultrasonic sensor's

Ultrasound can be very directional - what is the application? Help us to help you.

(you'd be surprised how often this question comes up)