WebSights

Speedtest is a very simple and straight-to-the-point tool to check your internet connection speed. It will show you (in kbps) how fast your download and upload speeds are. You can also compare how your ISP fares against others. Here is how they describe their site: Speedtest.net is a free broadband speed test with servers located all over the world. Compare your results with others and easily share them.

This is probably the most accurate net speed checker I've seen. They have a pretty cool interface too.