These provide three key measurements:
Download Speed:
The speed at which data is sent from the Internet to your computer.
Upload Speed:
The speed at which data is sent from your computer to the Internet.
Ping (Latency):
The time it takes in milliseconds for a small piece of data to be sent from your computer to the Internet and back.
Speed Test
TPG Speed Test
SpeedCheck
Goodgear Guide Speed Test
http://www.goodgearguide.com.au/speedtest/