Anyway, I spent $160 on a Garmin eTrex Venture HC bundle that included 100k topographic maps, which while not USGS hiker quality, are pretty good, and fun to play around with. This is a good solid (but relatively speaking low-end) unit that at this point does most of what I need it to do - point me at geocaches and record my trips. Dave did some digging around and came up with gpsvisualizer.com, a free website that will take a .gpx track file from a GPS and turn it into a track on a map.
The map below is the track of the geocaching trip that the girls and I took in Darlington Park this past weekend, and is immortalized below. Our track is the faint green line starting on Darlington Road, crossing under the railroad tracks, winding through the countryside, and returning. This is the functionality that makes Dave all tingly, and is possible with the out-of-the-box GPS and a few free websites and free software downloads. The below jpeg is the track overlaid over a USGS topo map.
The next pic is the same track overlaid over a black and white USGS aerial photo.
Note that in both maps, the majority of the track is in bright green, as we were at the lowest elevation along the creek. As the elevation increases, the color of the track changes through blue to purple. About halfway through the green track, you can see the minor detour off the trail we made to get the first cache, and later you can see the wrong trail we took before doubling back and going furthest to the right to get the last cache toward the top of the hill.
Unfortunately, the coolest overlay that you can do on the website (but not save as a jpeg) is to overlay the track on a Google satellite photo.
The application of this to a real hike, however modest, makes me drool. The GPS already records the distance travelled, the route and the elevation profile of the entire trip; these other free software downloads and websites turn that data into a trip map.