In order to learn more about tracklogs on your GPS, simply break down and read the short manual that came with the unit. If your unit is more that 3 years old or uses more than 2 AA batteries, you should upgrade. One important consideration is upgrading to a unit that has a memory card slot. In that case, you will be able to store considerably more data. In the case of my Garmin GPS 60csx, interacting with the memory card is actually easier than interacting with the unit. Also, it automatically creates individual logs on a per day basis. Very handy.
Please, please (!) rid yourself of the belief that you need to turn the unit off all of the time to save batteries. Newer units can run for 2-4 days on a single set of batteries when turned on and off at the beginning and end of the field day. If you are worried about wasting batteries, then use rechargeable ones and move on, man. In order to maximize the value of the track log, the unit should remain on during the entire day (except during lunch, when you change batteries, or when you are mapping underground).
A colleague at NBMG recently turned me on to a very handy program from the Minnesota Department of Natural Resources that easily converts GPS tracklogs and waypoints to shapefiles to use in GIS software. The program is called DNR Garmin and is extremely handy. Kudos to the author. The program can suck data right off the unit or can read from a gpx file. The image above is proof that it works.