If you look at just one cool web site today, go to Gutenkarte and check out any classic, but especially ones like Around the World in 80 Days. The AJAX-based map is based on OpenLayers that is available under the BSD license (that's real free, not gnu-speak for free) and will talk to any OGC compliant map server. The fine folks at MetaCarta are serving up both the Gutenkarte site and providing OpenLayers. Both are used in their commercial applications aimed at larger organizations (like governments) where they scan text to produce maps from large volumes of textual data. More on the API later.
We'll be posting a bunch more information about the Where 2.0 conference soon, but as a teaser, here's a really cool project that was just demonstrated at the conference, a non-Google mashup of maps and Project Gutenberg hosted classic literature called GutenKarte.