Last time we talked about viewing geocache locations in Google Earth before heading out on your cache excursions. You can also use Google Earth, and other mapping display programs, to view your GPS data (GPS tracks and waypoints) overlaid upon street maps and satellite imagery after you return from your geocaching excursion.
There are a number of applications available that will read your GPS track data and convert it into a format you can use to plot on a map or aerial image. One of my favorites is a free, web-based tool called GPS Visualizer. After you upload your GPS track and/or waypoint data from your GPS device to your computer (using a program like EasyGPS), go to the GPS Visualizer web site. There, you can import your GPX, LOC, or other GPS formatted file, choose your output file (Google Earth (KML), Google Maps, or a flat image file like .JPG), and press "GO!". When the conversion is finished, you'll have a map of your entire hike or ride. You can also modify the output options to view, for example, the elevation or speed profiles of your trek.
There are many other GPS file conversion and visualization tools contained on this web site. GPS Visualizer makes playing with your GPS data fun and easy.