NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
NetworkManager - NetworkManager is a set of co-operative tools that make networking simple and straightforward.
Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:
wicd - Wicd is an open source wired and wireless network manager for Linux.
Kismet - Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion detection system.
iw - iw is a new nl80211 based CLI configuration utility for wireless devices.