Google Maps + GPS + GPX

• Drag this Inject bookmarklet onto your bookmarks bar.


• Go to Google Maps


• Inject http://www.gnik.com/maps/google/loadgpx-0.0.1.js


• Upload the sample gpx file http://www.gnik.com/maps/google/test.gpx

Source: Link
GPX
Google Maps also accepts lat, long in decimal format as search parameter! (e.g. 33.8466, -118.1913)
Software (free) to download waypoints from your GPS unit to your computer in GPX format for upload to Google Maps