This week I was motivated to play with some of Yahoo's Geo tools after hearing a talk by Christian Heilmann regarding the same.
One tool in particular is his Geomaker application which "creates microformats and maps from geographical information embedded in texts". GeoMaker feeds your provided text into Yahoo's Placemaker service which will identify any geo locations referenced. Geomaker then massages this data into a Yahoo map widget which can be placed on any web page such as a blog entry.
Geomaker accepts either a block of test, a web page, or an RSS feed. The RSS feed option is a great way to quickly visualize to locations being referenced. For example, the following is a map of recent items from the Yahoo! World News RSS feed:
To stress test Placemaker and see how accurate it is, I dropped in the lyrics for Johnny Cash's rendition of "I've Been Everywhere". Results? It identified 70 place references and missed 22. The detector seems to be less accurate when given place names like this in a list. It does better when places are used in context, like the news articles above.
Here is the resulting map for "I've Been Everywhere" (minus the outlying countries Argentina and Costa Rica):