Moodgrapher: The World according to LiveJournal
Freakonomics is absolutely right on this one! A veritable plethora of paper ideas come out. I wonder if past data is publicly available.
Just a few ideas: Can we explain the weekend effect by looking at mood swings? Do people actually buy stock more when happy? Do credit spreads change as a result of mood swings? Can we time when we should sell a new issue?