Application wanted

Some time ago I read that Bill Clinton (starting in his younger days) would try to meet as many people as possible in a day, and then at night write down the particulars of everyone he met. It would be nice to have some sort of visual web app to do that. It would allow the user to note all of the relevant details about a person, and also visually show his connections to existing contacts, companies and concepts/entities. It can be done manually in Visio, but that’s hardly a workable solution. Does anyone know of any products that do this?

If not, then it goes on the list of stuff to build.