There’s a decent WiFi scanning tool built into Mac OS X Mountain Lion. This can be helpful when trying to diagnose interference issues based on channels and signal strength. It’s a bit tricky to find. Go to your hard drive, then the following folders:
System – Library – CoreServices
Then click on the app “WiFi Diagnostics”. Then a window pops up to help you create a diagnostic report. I ignore that and just click on the top menu:
View – WiFi Scan
Then you’ll see this handy program:
If you use this program a lot, you can drag it to the desktop or your Applications or Utilities folder.