I have used this service from Speedtest.net extensively in the tech field, and have always been impressed by the ease of use, test speed and accuracy that this application delivers. The same stands for the iPhone and iPod Touch version.
Speedtest gives iPhone and iPod Touch users a quick, thorough look at a complete set of network stats. In under 20 seconds Speedtest whips out a download test, an upload test, and a ping test ,as well as determining the network type, the server location, External/Internal IP addresses and using the GPS feature, an exact Latitude/Longitude location for the device. The last feature I find to be very cool, I am not quite sure why, but it is. Something about knowing exactly where I stand I guess, or maybe its the Magellan-like adventurer in me.