Today Google announced the opening of the United States in Google Map Maker. This allows you to add your own expert local knowledge directly to the map. According to Google, "you know your neighborhood or hometown best, and with Google Map Maker you can ensure the places you care about are richly represented on the map. For example, you can add the name of your local pizza parlor, or add a description of your favorite book store.
Google wants you to help make the map complete in other ways as well, such as marking the bike lanes in your town or adding all of the buildings on your university campus so they appear in Google Maps.