Windows Vista only: 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. What sets Vistumbler apart from the rest is its support for GPS and live Google Earth tracking, which plots hotspots on a map. The whole thing is really cool, but unfortunately I (and I suspect many of you) don't have the tools on hand to try out the really impressive features. Still, Vistumbler is an excellent tool even without without the GPS to Google Earth mapping. Vistumbler is free download, Windows Vista only. If you're on XP and you want similar Google Earth integration with NetStumbler, check out Earth Stumbler. Thanks VashtiDunlop!