loxtrax , available via
www.magnalox.net is a very cool application for just this. Small, yet very versatile. Best of all, it's completely free. It also supports logging of trips, and gives you some statistics. The logfiles can be analysed further on your PC, with an application of choice.
Another cool factor is that your entire route is displayed, and you can even use these to overlay them on for instance Google Earth
Bart