WiFiFoFum by Aspecto Software is a Wi-Fi WLAN Scanner & Visual Radar application for Apple iPhone and iPod Touch mobile devices.

WiFiFoFum scans for 802.11 wireless networks and displays information about each detected network such as SSID, MAC address, RSSI (signal strength), channel, Access Point (AP) mode, security mode and transmission rates. The radar display provides a graphical representation of nearby WiFi access points.

Note that the visual radar feature is not perfect yet. It does not actually display what direction the signal is coming from but estimates distances and represents it on the map based on signal strength.