WiFiFoFum is a WiFi scanner for Windows Mobile based Pocket PCs and Smartphones.

Some of the features it offers are:

-List view showing information such was WEP, SSID, MAC, signal strength(RSSI), latitude, longitude and location precision (HDOP)
-Radar view shows distance to access points from current location
-Aggressive scanning mode to find even more access points
-This software can actually block the “New wireless network found” message

WiFiFoFum