For runners and cyclists, you can record your route, average speed, time elapsed, distance and change in altitude really easily. Save a route and you can repeat it and compete against your previous time, or just set yourself a target.
In addition to this personal information, you can choose to upload it to a website where it can be viewed by anyone, and compared to other users. If you're doing group training, or a known route you can see how you stack up against the competition.
The interface on Marathon is really intuitive and simple, and it's easy to get started. You need to have the Microsoft .Net 3.5 framework installed, but otherwise you shouldn't have any problems. Unfortunately, the application won't let you convert or upload the data to other formats, like KML, which could be displayed to anyone with Google Earth.
If you want to time, and keep track of your movement and speed, Marathon is a simple and neat way to do so.
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