Computer Aided Carpooling?

Bill Phu asks: "I just had an idea for an interesting open source and/or freeware add-on (for a commercial package). While on the crappy bus ride to work this morning, I just realized that car-pooling would be a much better idea, but finding people to carpool with is a pain in the butt. But the chances of someone living near you increases if the organization (e.g. company or university) is larger. Wouldn't it be great if there was a tool to help you find people to carpool with?" Read on for the details on this idea and tell us what you think.

"My idea is to create a program (or a free web service?) that would help you find people to carpool with to/from work. Traditional bulletin boards are a pain. What would be better if there was a database of streets and people who want to carpool. People would (voluntarily) list themselves into the database, and if they have a car that they can carpool with or not. The program would sort out, geographically, a list of eveyrone else in the database that lives near other potential carpool users, or within a specified distance along the path to/from work.

E.g. If you are looking for a drive, you could list all potential drivers within, say, 1 km of where you live. People with cars can list people who need a drive within 1 km of where they live, or within 500 m of their path to work.

I know there are several packages available commercially that could do the hard calculations easily. They tend to be pricey GIS packages, although there are freeware ones out there e.g. GRASS; or cheap ones like Idrisi (although idrisi doesn't handle topology very well, I don't think..). What does not exist, at least not that I know of, is software to geo-encode addresses to geographic locations (e.g. so an address like 7071 Mumford Road could be translated into a reliable spot on a map). Also, I cannot think of a public streets database that is useable (I wonder if the HRM will license it free to students to work with?).

So would any of you guys know of a geo-encoding tool or any other software that can do this?"