WiFi Hopper is a WLAN utility that combines the features of a Network Discovery and Site Survey tool with a Connection Manager.
Sporting a comprehensive arsenal of network details, filters, RSSI graphing and built-in GPS support, WiFi Hopper is invaluable for identification and advanced characterization of neighboring wireless devices.
Additionally, WiFi Hopper can connect to unsecured, WEP, WPA-PSK and WPA2-PSK networks directly from within the application. With editable network profiles and dedicated Connection Manager execution mode, WiFi Hopper can be used as a significantly more transparent replacement for Windows and manufacturer-provided wireless clients.
Category:   Software > Monitoring/Scanning

KisMAC is an opensource and free stumbler/scanner application for Mac OS X. It has an advantage over MacStumbler/iStumbler/NetStumbler in that it uses monitor mode and passive scanning.
KisMAC supports several third party PCMCIA cards - Orinoco, PrismII, Cisco Aironet, Atheros and PrismGT. USB Prism2 is supported as well, and USB Ralink support is in development. All of the internal AirPort hardware is supported as well.
Please note: This program is not intended for novices, but for professional users. Take this as a warning
Category:   Software > Monitoring/Scanning

InSSIDer is a free Wi-Fi network scanner for Windows Vista and windows XP. Because NetStumbler doesn't work well with Windows Vista and 64-bit Windows XP, we decided to build an open-source Wi-Fi network scanner designed for the current generation of Windows operating systems.
Category:   Software > Monitoring/Scanning

WaveWatcher is a network management program for the monitoring and logging of wireless networks.
Category:   Software > Monitoring/Scanning

is another applett which shows how far away you are from the base-station.
Category:   Software > Monitoring/Scanning