Sorting users geographically...

I'm helping a friend of mine build a matchmaking website, and we have a doozy of a problem to solve: What I need to do is two fold: #1 Collect whatever geographical information I need from each user to enable #2 #2 Be able to run query's to find people NEAR (geographically) another person. Does anyone know of any commercial or free implementations of this? Is it primarily a database problem or is their some way (computationally) to compute the probable proximity of two zip codes? Hopefully someone responds to this with a Pear package that does exactly what I need! :) If that can't happen, then I'd appreciate any options you can think of. td -- Free Linux Technical Articles http://www.linuxtecharticles.com