TwitterMood is a Google Maps mashup that rates moods across tweets. They hook into Twitter via the gardenhose to consume 1.8m tweets daily. There is both a graph showing the past few days and the colored mashup that you can zoom in and out of.
The range goes form unhappy to happy. Currently it seems the United States is in meh for a mood. Sort of suits those around me.
Big thanks to @SarahInTampa for pointing this one out.