I have a GPS unit (Garmin Zumo 450) that I use on my street bike, but for some reason it never occurred to me that you would use one on a dirt bike. Maybe because I live on the east coast and don’t go trail riding anywhere I’m likely to get lost… But there are trail areas in national parks in this half of the country that are certainly big enough to get lost in.
A GPS unit will also allow you to participate in geocaching – a great addition to trail riding. Geocaching is basically a high-tech treasure hunt. Caches are hidden and listed on the Internet (try Geocaching.com) with only their coordinates and sometimes additional clues. The caches generally include a logbook and pencil to record visitors, and tokens or prizes that can be traded.
The author also discusses using the GPS and some additional software to map your own trails, and build your own maps. If you’re interested in such things have a look at the whole article.