Google Map of The San Andreas Fault:
This Google Map shows the approximate trace of the San Andreas Fault as a red line. Zoom in to see houses, bridges, roads and more that are built near the fault. It was created by measuring the latitude and longitude for many points along the fault trace from maps published by the United States Geological Survey, California Geological Survey and other sources (a detailed list of these publications can be seen here)
Other Geology.com Google Maps: Meteor Crater Map, US State High Points Map, Sahara Desert Map, Plate Tectonics Map
More Weather & Earth Mashups here..
My Hotel Room Google Maps Mashup:
My Hotel Room - Here's a cool US Google Maps mashup that will help you quickly find hotels in close proximity to Airports, Landmarks or by City & State or specific Hotel Chain. I like how easy and quick this mashup is to use but for those that are trying to visibly landmark where the hotel is, the option to toggle to satellite view might be a nice user interface addition to consider.
HeyWhat's That Google Maps Mashup:
A description from the creator: "..You're at a highway rest stop or on top of a mountain. You see distant peaks. What are they? HeyWhatsThat provides panoramic sketches and the names of visible peaks for just about anywhere in the United States. You can browse panoramas that someone else has requested and generate your own. And you can do it via web, email and phone."
HumanServices.Net Google Maps Mashup - This is a great Google Maps enabled Human Services website for people living in Southern Pennsylvania. To see the mashup in action type "addictions" into the search field or expand the tree from the left. Switch over to "Map" view to see results from the community listings database plotted on a nice Google Maps user interface. Users can even plot listings by neighborhood, within their school district or within a 5 minutes walk of a specific busline. The same creators also have 2 other mashups: Outdoor Recreational Activities and After-School Activities for Kids. All of these are great, functional community Maps mashups that serve to benefit these local communities by making this information easier to find.
U.S. EPA Superfund Site Locator - The U.S. EPA's latest release of their Superfund data (in XML format) mashed up with Google Maps to create a Superfund Site Locator. The map creators, terra IMS, is hoping to spread the word to environmental non-profits as well as the public at large about the locator.