Lots of fun sites being created with Google Maps--MIBazaar is my current favorite. It combines Google Maps with a local RSS news feed by zip code; plus local traffic news so you can see where the accidents are. The "About Me" is geographic so you can see on a world map where the site creator was born and went throughout his career.
Google Maps Mania keeps up with new sites influenced by Google Maps.
My own thoughts on applications focus on smaller areas, such as specific buildings, or micro maps of small objects.
Are any libraries developing anything along these lines? One obvious idea is a tour of the library, geographically moving through each section--circ, reference, special collections, and so forth, and at each stop include a description, photos, services, and internal links.
I imagine it would benefit the websites of most public/academic libraries to include mapping features focusing on local restaurants, nightlife, traffic, news, etc.
Companies with hundreds of employees in a high-rise building might link each floor plan with the location of each employee as a stop, and include bio information, current projects searchable by keywords so employees from different departments can discover if others in the company are working on similar things, and so on.
library2.0, librarians, libraries, Google Maps