I wander around a lot, and connect to a lot of wireless networks. What is the best way to manage all the networks and keys?

I am thinking of something that scans for networks and gives you a list of available APs, then lets you pick one and type in the key, then remembers it until next time you wander over that way.

Or just let me know what people that wander quite a bit like to use to get online quickly. This is all assuming I have the necessary key, or the AP is open.