Transfer Software GPS-PC

Free, easy to use program
Extensive program with many options of format conversion (freeware)
Conversion track < > route (Garmin)
Transfer software (ideal for forerunner 205 / 305)
GPS TrackMaker
Freeware program to the transfer and edit GPS data. Import and save in various formats.
GPS Visualizer
Online GPS data converter for various formats such as: GPX, KMZ, etc.

GPS Format Conversion Tools

Konverter von
Online Converter for the formats Google Earth (KML and KMZ), PCX5 Tracks and waypoints, GPX Tracks, routes and waypoints, GPX for Garmin StreetPilot, Garmin course (CRS and TCX), GeoRSS, logbook, NMEA, OVL (ASCII), Fugawi, KOMPASS Verlag (Alpenverein), NAVIGON route, OziExplorer, qpeGps track MagicMaps ICT, TomTom ITN, Suunto SDF, Magellan Track, PathAway
GPS-Babel von GPS Visualizer
Online conversion tool also for exotic formats
Konverter von GPS Visualizer
Online conversion to the output formats txt, gpx and kml

3D Displaying Software

Google Earth
Great and easy to use 3D program (free of charge)
World Wind
Free 3D software of the NASA. More extensive than GoogleEarth but this more complicated to operate.

Mapping Software

Freeware with interesting features such as calibration of scanned maps, autom. Download of elevation data (SRTM the), creation and visualization of tracks, upload tracks to GPS, GPS file conversion, creation and upload of "Garmin Custom Maps" (only for newer Garmin devices) etc. Certainly worth a test!
Widespread, paid program for various tasks relating to track creation and editing.
Touratech QV
Very comprehensive and therefore complex mapping program. Need some training time, but after much fun (relatively expensive).
GPS supported training software (freeware). German-speaking Forum.

Navigation Software for Mobile

For Pocket PC/Windows Mobile 5 or 6 and PALM. 15-Day trial version to download and reference for example at Touratech (German)