The Mother Road: Historic Route 66 – a great information website has “Turn by Turn” maps that identify where Route 66 is, since some of the original road is no longer, and most of it isn’t marked with highway markers anymore.
Turn by Turn Route 66 in Google Maps – Some kind Google Earth enthusiast has taken the maps from the site above and plotted them out using Google Earth/Maps. Awesome!
Photographic Interests in Illinois along Route 66 – Someone else marked famous landmarks in Illinois via Google Earth. Nice, handy.
However, if you just want to follow along with the song – there’s a google earth map for that, too.