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This is a very dynamic and exciting period for interactive data and map applications on the Web. This great dynamism is driven (but to some extent also drives) by the numerous innovations and trends that are currently undergoing within the complex Web scenario (users, industry, standards, innovation...). Very briefly:
To some extent, different browser vendors are finally converging more towards a wide adoption of Web Standards. A relevant example for data and mapping visualizations is SVG that, although around as a Web standard since 1999, lacked until recently wide adoption, because of Internet Explorer not supporting it until version 9.
If JavaSript (and HTML5) is the big winner, Flash is the loser. You can still find Flash applications around the Web (your example is a beautifully designed interactive Flash application), but its technology is clearly PAST.
vizzuality. These guys from Spain are amazing. There interactive visualizations are stunning. They also have a Web product called cartodb that lets you upload data to a PostGIS server and create awesome visualizations. And look out also their HTML5 mapping experiments, to have an idea of where the technology is heading.
Stamen, not my personal favorite, but still very good and full of innovative ideas.
About and around d3.js:
Kartograph. Simply beautiful maps and visualizations.
Leaflet. One cannot avoid mentioning this library for its huge following among today's Web designers and programmers.
And Web examples: