A Location Based Service Somebody Needs to Develop

As someone who spends lots of time at conferences and trade shows, and who randomly bumps into people, it occurs to me that one location-based service that would really be helpful is a way to have your mobile alert you when somebody you have been communicating with over a recent user-defined period is in your vicinity. The reason is simple enough: quite often one works with people for years without ever physically meeting them. And if the opportunity presents itself, one would like to stroll over and say hello.

The issue is that I don't know how well GPS will work when all of us are inside a large meeting hall. Bluetooth would help for short distances, I suppose. It might also be nice if the app could run in the background when synchronized with one's notebook or desktop and collect photos of your contacts, putting them into your contact database so you know roughly what the person you want to meet looks like.

For that matter, scouring public sources and putting a picture into my contact directory might also be nice if I weren't a Facebook user, which essentially provides that function.