Want to keep up on the latest map mashups*? Google Maps Mania is the unofficial blog of all things GoogleMaps. New georeferenced applications are emerging almost daily - some goofy, some more serious.
Whether this is the sort of thing that floats your boat or not, it's worth keeping an eye on. Sooner or later, someone's likely to hit on an application you can't imagine ever living without.
* Mashups are hybrids of older applications and/or content (e.g., GoogleMapping Craig's List). There are some interesting musical experiments along these lines, as well.