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 fea