Vistumbler 10.8.2 WiFi network scanner for Windows

Vistumbler is a free, open-source application Vistumbler scans wireless networks within range of your Wi-Fi antenna, tracks signal strength over time, and handles pretty much everything else that other apps of this kind do. It is a free and open source network monitoring application that's light on system resources and well-designed.

Here are some screenshots to illustrate the features and user interface of this application: