Nike+ is nothing new, as its been around since May 2006, but it is definitely one of the most underrated "run trackers" on the market.  With all these fancy GPS "run trackers" like the Garmin 610, a touch screen gps watch (pic below), how does Nike+ stack up?
Well, I've ben using my Nike+ sportwatch, and sensor combo, seen in the picture below, for about a year now.
And I have to admit, as much as I would like one of those sleek (although pricy) GPS watches, the Nike+ system is actually very accurate.  During my runs, I can easily look at stats, such as: calories burned, stopwatch, milage, mile pace, and time of day.  And best of all, the nike plus watch has a usb port to plug into a computer, where you can upload your run onto www.nikeplus.com  Here, you can se detailed graphs that show milage, speed, and more!  Also, ou can set goals, join challenges, and even compete with friends.  Also, If you have an ipod touch, or an iphone, you can download the free nike+gps app to track your runs without a sensor.


Pros: 
Pretty Accurate
Easy to use
Cool Graphs on the website

Cons:
Sensor should come with a way to attach it to any shoe, not just nike shoes
Nike Plus website is laggy