A copy from this site. Because I use it often.
Pushpins: http://maps.google.com/mapfiles/kml/pushpin/
Palette pal2 : http://maps.google.com/mapfiles/kml/pal2/
Palette pal3 : http://maps.google.com/mapfiles/kml/pal3/
Palette pal4 : http://maps.google.com/mapfiles/kml/pal4/
Palette pal5 : http://maps.google.com/mapfiles/kml/pal5/
Paddles: http://maps.google.com/mapfiles/kml/paddle/
Style
Style -lv
Style _maps
Track Directions: http://earth.google.com/images/kml-icons/track-directional/
Miscellaneous Google map Icons : http://maps.google.com/mapfiles/ms/icons/
Add .shadow for shadow version of most icons e.g. POI.shadow.png