This is a KML network link that can display 5 different OpenStreetMap map overlays in Google Earth. It allows you to view these maps in 3D and together with your other favourite layers. Read the main page for how it works.
Download the file
openstreetmap-layers-for-google-earth-combined.kmz (version 4) and open it in Google Earth. Alternatively, for a combined file of all 33 map sources on this site, go here.
OpenStreetMap Mapnik (
http://www.openstreetmap.org/ ):

OpenStreetMap Mapnik B&W (
http://www.openstreetmap.org/ ):

OpenCycleMap (
http://opencyclemap.org/ ):

OpenStreetMap Hike & Bike Map (
http://hikebikemap.de/ ):
OpenStreetMap Public Transport (
http://www.öpnvkarte.de/ ):

Do you have comments, bug reports, or suggestions for other map sources? Please leave them below.