Xirrus Wi-Fi Inspector
If you're a frequent user of Wi-Fi hotspots, you'll find this free software an invaluable tool, especially if you need to troubleshoot connections. Xirrus Wi-Fi Inspector finds nearby Wi-Fi networks, gives an extraordinary amount of information about each, manages your Wi-Fi connections, and monitors and reports on network speed and performance.
For each network that it finds, Xirrus Wi-Fi Inspector tells you whether it's encrypted or not and if so, what encryption it uses; the signal strength; manufacturer of the router; what channel and frequency it uses; and whether it's an access point or a peer-to-peer connection--and more as well.
To help troubleshoot, the software also displays your IP address, information about your adapter and IP configuration. In addition, it pings your configured DNS server and gateway to make sure they're active and alive.
There's plenty more here as well, including a speed tester. The software is a more powerful version of Xirrus's free Wi-Fi Monitor, which runs as a Vista gadget. Both pieces of software are immensely useful for people who frequently connect to Wi-Fi networks.
Note: Although the vendor does not support this program on Windows 7, it worked fine on my Windows 7 test system.