Google Maps now integrates with Wikipedia (click "More" tab). Concharto is a geographic wiki for documenting historical events. Flick also has a map service.
posted on May 14, 2008 - View this thread

Train tracker.
posted on Jan 21, 2008 - View this thread

MTBGuru is a new site that enables bikers, hikers and runners to upload GPS info, along with photos and comments, from their routes that get mashed up with Google Maps to create an ever-expanding trail resource. Mostly Bay Area now but that is changing.
posted on Nov 29, 2006 - View this thread

Why not mashup Google maps and NOAA's digital forecast database? Enter a zip code, a city name, or just point and click on a map (continental US and Hawaii only, alas). A 5 day forecast will appear at the bottom of the screen (including some cheesy little pictures illustrating, like rain and fog, just in case you forget what they look like).
posted on May 18, 2006 - View this thread

Celebrity Maps is a google maps/stargazing mashup that makes stalking your favorite star so much easier. And it doesn't even cost you $5 on Sunset.
posted on Nov 15, 2005 - View this thread