Members at Geocaching.com can download a file from their account page that will enable Google Earth to show where geocaches are, providing links to cache pages. Its also possible to download a track from a Travel Bug page, which lets you view a 'fly through' of the travel bug's journey.
Be warned that the KML files downloaded from geocaching.com are deliberately made inaccurate - cache locations may be shown many meters from where they actually are. Also, as you move the map around, the caches will change position. For this reason, it's hard to use the geocaching KML file to locate caches precisly.
Google Earth is available for Windows, Macintosh, and Linux.