AutoAP is a script that continuously scans for open Wi-Fi connections, tests them for validity, and connects to the strongest signal. If the connection is lost, the script scans again and finds the strongest valid signal again, and maintains a continuous connection to the internet in a mobile or portable environment. The script paremeters are highly configurable, including ability to configure secure connections.
iStumbler is the leading wireless discovery tool for Mac OS X, providing plugins for finding AirPort networks, Bluetooth devices and Bonjour services with your Mac.