WiFi Map - A crowdsourced list of routers and passwords
NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
WifiMapper - Find free WiFi anywhere in the world
inSSIDer - inSSIDer Essential makes it easy to maintain small business WiFi.
Instabridge - Crowdsourced free wifi (now on Android)
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.