This site is cool. You can check your internet speed and compare to other people on your ISP. They also have a Speed Index that shows the average internet users speed at any given time. You can also run a scheduled test to monitor your line to find what hours of the day your internet performs at it's best.
After you test you can share your score on twitter or facebook. The newest sharing options allow you to share a dynamic image in your blog or website (or as a forum signature) that updates with your most recent test information every time the image is requested.
Pretty cool way to make sure that your ISP is giving you what you pay for.