NetStumbler is a tool for Windows that allows you to detect Wireless Local Area Networks (WLANs) using 802.11b, 802.11a and 802.11g. It has many uses:
• Verify that your network is set up the way you intended. • Find locations with poor coverage in your WLAN. • Detect other networks that may be causing interference on your network. • Detect unauthorized "rogue" access points in your workplace. • Help aim directional antennas for long-haul WLAN links. • Use it recreationally for WarDriving.