Big image at YosemiteThis free program allows you to plan and record your hiking and mountain bike trips with a Garmin eTrex GPS receiver and share your local knowledge of trails with others. You can also use the program to print topographic maps with these trails, either on a single page or as a mosaic on many sheets of paper. And you can use the program to visualize planned or past trips in 3D by virtually flying across a landscape of colorized aerial photographs draped over a three dimensional terrain model. This program is not intended or suitable for such applications such as automobile or aviation trips which cover large areas of terrain.
If you are interested in terrain visualization but this program doesn't meet your expectations, see Terrain Visualization for programs with similar capabilities. If you have an older (than eTrex) model Garmin or use a Magellan or Brunton or Lowrance GPSR and need topographic mapping capability, or you have trouble with this program I can recommend the moderately priced Expert GPS from Topografix. (I received a free copy of ExpertGPS from Topografix for collaborating with the design of the GPX file format).
I didn't post a big img here just in case someone uses dialup.