This huge billboard near New York City's Madison Square Garden was constructed by the Deutsche Bank with assistance from MIT researchers. It measures carbon emissions monthly, and then averages them for a steady incline, broadcast for all to see.
So it's not exactly "real time," but it's fairly close, according to BusinessGreen. The amount of greenhouse gases, now thrown in our faces by this giant glowing billboard, is rising by about 800 tonnes per second, which doesn't mean much to me but certainly sounds like a large number. You can also download a widget in case you don't walk by the billboard itself too often but still want to see a big number slowly increasing. [Treehugger]