NetSpot - NetSpot is a free app for wireless site surveys, Wi-Fi analysis, and troubleshooting
Nmap - Nmap Free Security Scanner, Port Scanner, & Network Exploration Tool. Download open source software for Linux, Windows, UNIX, FreeBSD, etc.
Vistumbler - Vistumbler is a wireless network scanner for Windows Vista and Windows 7. Features:
SolarWinds Network Configuration Manager - SolarWinds is a leading provider of powerful and affordable IT infrastructure management software. Make IT look easy.
Wifi Analyzer - Wifi Analyzer is a handy tool which helps you to select a better channel for your wireless router.
Cisco Network Assistant - Cisco Network Assistant simplifies wired and wireless network management, and provides critical product information using Cisco Active Advisor.