Google Maps Mashed With Census Data ; Use the map like your normally would; the red dots will refresh as you move the map around and zoom. : http://www.gcensus.com/index.php

Voronoi treemaps for the visualization of software metrics : pdf available at http://portal.acm.org/citation.cfm?id=1056018.1056041 uses engaging 'chickenwire' grid.

American Memory maps are “zoomable” and can be examined in detail using Lizard Tech’s MrSID technology (making it possible to view and work with these maps "offline.") : http://lcweb2.loc.gov/ammem/ndlpedu/features/maps/introduction.html

Visual Learning/communication Blog : http://graphicfacilitation.blogs.com/pages/

Principles of Visual Displays of Information:
Always enforce data comparisons: “Compared with what?”
Show causality: “How could this have happened?”
Show multi-variables: “How much change? How long? How many factors?"
Completely integrate words, data and images: “What can you do to bring more clarity to the issues?”
Content is king: “How can a designer do no harm to the content's substance, quality, integrity, and purpose?”
Information is stacked in space(and time)
Use small multiples: “How can we see the sun rotated? Record it's sunspots over time!”

An aerial view of the Sacramento River that is woven into a carpet for the floor of a pedestrian bridge : (from http://googlemapsmania.blogspot.com/ )
http://here2day.netwiz.net/seyedsite/publicart/flyingcarpet/flyingcarpetframe.html