I got a Garmin Forerunner 305 for my birthday this year, just thinking I could use it to track the distance I was running. To my surprise, this cool device does a whole lot more.
First, it comes with a client so that you can download all your runs,bikes, whatever to your machine and analyze and aggregate your distance, heart rate, plot them versus speed and elevation and more.
But even cooler is a website called MotionBased.com where you can upload your runs straight to the website via a browser plug-in. Here you can do a whole lot more such as share your runs, and of course plot mash them up with Google Maps.
They are starting to build some site widgets, but have a long way to go. Right now you can share a specfic run (see below) - but what they really need to do is have a widget that always shows your latest activity etc. Then of course, a FaceBook app.
Anways, if you are into running or biking a lot this is a must own device. It's also a great device if you are just starting and having trouble getting motivated. It's definitely motivating to add to your stats, see where you ran on a map, and see how you are improving.