iStumbler was the first wireless connection tool I installed on my Mac. Don't get me wrong, the one included in your Mac is fairly good, but iStumbler just offers more features.
I like the simple interface and how it separates networks by type (ie AirPort, Bluetooth and Bonjour). You can immediately see which ones are open and which ones are secure, and the signal percentage gives you an idea of the strength of the network and if it's worth connecting to it. iStumbler also includes an evolving graph at the top of the interface that will display the stability of the network you have selected.
The application comes with an AirPort plugin that provides more accurate information like dBm values.
It's a shame that iStumbler hasn't had an update in a while. This is a good piece of software and it'd be great to see a bit of new features built into it.
iStumbler remains an excellent app for finding wireless connections around you.
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