It's old news (to some), but I finally got around to playing with the Twingly blog visualizer (via 3PointD). For those who can't tell from the picture to the right or from the video at the bottom of this post, Twingly is a downloadable application that displays a rotating 3D globe that includes plotted locations of blog posts as they occur in real-time. Basically, the longer you let it run, the more you'll see where blog activity is occurring around the globe. Statistics for each country are available in the big ring circumnavigating the globe. The application is available for download here and you can even turn it into your screensaver.
Google has something similar to this at their headquarters that plots geographic search volumes on a giant globe, also, although that isn't available for public consumption. Overall, the direct marketing applications of something like this are probably pretty low, but it may provide for interestingly analysis and it's certainly an excellent graphical representation of the blogosphere.
Another great example of this is the 3DLiveStats.com application (the link appears to be down at the moment), which allows you to plot data from any external database on a giant 3D globe.