An 802.11b wireless network detector for Windows 2000/XP/9X. It uses probe requests to detect access points. This is extremely noisy and obvious to a network admin worth his salt (the packet contents are "All of your 802.11b are belong to us"). Which may or may not be a bad thing depending on what you're using it for. This active scanning also prevents it from detecting cloaked networks. The plus side to using netstumbler (as opposed to something like kismet) is that it displays information in an easy to read format. Including a nice bar graph of the radio signal. It can interface with a GPS device to keep track of network locations.