Test the speed of your Internet connection.

While there are many sites that offer this service, my favorite has to be Speedtest.net. They have a great user interface which allows you to perform the test using one of a multitude of servers around the world (the default is the closest to your geographic location). They also maintain a history of all your tests so you can go back and look at past results. You can also get statistics for internet connections all over the world. Pretty neat if you're a huge Internet nerd like I am.