Came across this last night when I couldn't sleep (yes I'm even looking at maps at 2am :)).
It started through a great blog called Kelso's Corner. It's a cartography/visualizations oriented blog/website, but he posts examples of some great (mostly interactive) cartography. A lot of them, not surprisingly, come from the New York Times. Newspapers don't always produce the greatest or most appropriate maps, but the NYTimes seems to make the extra effort at doing this (The Economist is another one that does a great job). Anyway, I "discovered" that they have an interactive visualization creator called Visualization lab. They have a number of visualization techniques available for the user to create their own interactive visualization. According to this, it is based on technology from IBM Research. I didn't explore too deeply, so I don't know if the NYTimes site allows you to load your own data, but the Many Eyes does. Honestly, I'm a bit wary of these types of "map your own data" neogeography things. But I think the NYTimes site has done a great job of restricting users so that they make an appropriate map (e.g. a choropleth using derived data instead of raw counts). They are even using a good map projection for their world map data! I'm not too keen on the bubble visualization, because when I see it I expect the countries to be in the right place, so I find it hard to read. I guess I couldn't really find any order to the arrangement (hey I'm a Geographer, I look for spatial patterns automatically). Either way, I thought it was pretty well done, and fast.
Naturally when I see something like the Visualization lab, I immediately think "How can I do that?" Well the NYTimes has made it easier for me to try and make my own. They didn't release the code or anything, but they now have their own data API. One of the first that they have released is the campaign finance api. I believe this would be the same data used for creating this interactive map.