I use a GPS for lots of stuff but mainly hunting related.

Scouting - Mark sign, trails, stand sites, possible stand sites and anything else that might help.

Hunting - I tell it to take me to the stand site I want to go to. You can make a route if you want to go a specific way. It gets me there very fast even in the dark. I can stay until dark, even if I am way back 1/2 to 1 mile. I tell it to take me to where I am parked and follow the arrow. Very fast and not much fumbling around in the dark.

In-Season Scouting - I mark all of the sign I see during hunting season so it kind of keeps me up-to-date on new movement patterns and such.

I currently have two different ones but if I only had one I would recommend the Garmin 60CSX. I would also recommend some good mapping software like DeLorme Topo USA.

http://gpsinformation.net/

http://www.maps-gps-info.com/gp.html

http://www.gpsy.com/gpsinfo/