Web Seer is a fascinating tool that lets you explore what questions people are typing into Google, and compare it to other questions to see where they overlap. Admittedly, I can’t think of a real world use for this, but it’s fun to play with. If you find an interesting comparison, please leave a link in the comments!
More info on the Web Seer project page.
Stupid Fight is another site that performs a fun comparison: Which Twitter celebrity has the dumbest followers? It works for non-celebs too.
Stupid Fight can’t go out and administer an intelligence test to each person that’s sending messages to a celebrity. So instead, it estimates based on several stupid indicators. Are they using twenty exclamation marks in a row? Do they endlessly use the abbreviation ‘OMG’? Do they seem incapable of working out where their Shift key is? These indicators have a strong correlation with the message, and its sender, being stupid.