After more than 100k downloads on iOS platforms, Network Utility comes also to OS X with Network Utility X, a complete set of network tools.
I am changing networks and testing access points frequently. It is very handy to have this to quickly tell me most of what I need to know in one place.
Great little utility that I've ended up using daily. I had a question/suggestion for the developer and they responded quickly and pointed out that my suggestion was already in the application. I'd rate it if that was the scale used.