Background Information

• Wikipedia—general information and links out to many resources. A useful place to start if you do not have a good understanding of what a map mashup is and how mashups are used. 
• 100 Things to do with Google Map Mashups—Every publication should do at lease 10 of these. 

Google Specific Map Mashup Information

• Google Maps Mania—"An unofficial Google Maps blog tracking the websites, mashups and tools being influenced by Google Maps." Best source for latest, breaking news, tips and insights on how Google Maps are being used around the web.
• Mapki—A Wiki specifically for Google Map Mashups. Has a list of more than 700 projects. 

Google Map Mashup Tools

• Spreadsheet Mapper—This is the spreadsheet tool that we use in the Tech Training Workshops. With this tool you can "bulk map" dozens or even hundreds of points in good-looking balloons using the Google Spreadsheet Mapper 2.0 templates. This link takes you site where you can get the spreadsheet and where you can watch a short video on how to use the template.
• Map a List—A non-Google tool for creating maps from a list of data. This is a step-by-step tool that has different display options than the Spreadsheet Mapper. I find the Spreadsheet Mapper a better tool. Your mileage may vary.

General Map Mashup Tools

• GPS Visualizer—This is the tool to use to generate latitude and longitude information from addresses (no zip code required). "GPS Visualizer is a free, easy-to-use online utility that creates maps and profiles from GPS data (tracks and waypoints), street addresses, or simple coordinates. Use it to see where you've been, plan where you're going, or visualize geographic data (business locations, scientific observations, events, customers, real estate, geotagged photos, etc.)." —from GPS Visualizer home page.
• Geocoder.us—If you have a major geocoding project and need thousands of lookups, take a look at geocoder.us. 20,000 lookups cost only $50. This is also a good source of information on geocoding and the site has an active blog with information on new features and examples.

Beyond Map Mashups

Examples from the Tech Training Workshops

• San Diego Fires
• San Francisco Oil Spill
• Oregon Wind Storm
• Weather Information Aggregation (Weatherbonk)
• Housing Map Aggregation (Craigslist Informtion)
• Kansas Unsolved Homocides
• Houston Crime Map
• LA Times Crime Map
• Roanoke Snow Map