inSSIDer - WiFi scanning software
YOU CAN
– Inspect your Wi-Fi and surrounding networks
– Scan and filter hundreds of nearby access points
– Troubleshoot competing access points and clogged Wi-Fi channels
– Highlight access points for areas with high Wi-Fi concentration
– Track the strength of received signals in dBm over time
– Sort results by MAC Address, SSID, Channel, RSSI, Time Last Seen
– Export Wi-Fi and GPS data to a KML file in Google Earth

Download
http://www.metageek.net/products/inssider/download/