WIFI Studio is an 802.11 (WIFI) Scanner for Windows Vista, much like Netstumbler but for Vista.
Features over the standard included scanner in windows Vista:
Ability to connect to a particular access point by MAC address. This feature is usefull say when there are 5 access points with 'linksys' as the SSID, but they're not really part of the same network. Vista assumes all like-named access points are part of the same network.
Trace window that lets you see what's going on inside Vista's auto-connect logic.
Graphic history of signal level for each visible access point.
And much more.