Here is a personal, non-commercial page where they keep a list of all F1 tracks ever (since 1950), to be seen in Google Earth. It includes all current NASCAR and Champcar circuits and many more (it has around 250 tracks right now and it'll have a huge update soon).
Each track has a link to its wikipedia page, its layout and its webpage. Most current F1 tracks include a "virtual lap" using the "Play Tour" feature of Google Earth.
Tracks in Google EarthThis is Magny-Cours:
They use a public host, so apologies in advance if you find that the site is unavailable (some times it is overwhelmed by the amount of visitors... sorry).
They have also modified the Wikipedia pages on current F1 tracks to include a GoogleHack by Magnus. It is in the top right corner of the page (the link labeled as "Coordinates". Clic on it and you will open Magnus's page where you can see the track using several software for mapping, from Nasa's WorldWind to Yahoo, MSN or Google Maps.
Here is an example (at Albert Park) of what they did:
Enjoy!
