If Twitter is voyeuristic, then TweetPsych takes it to a whole new level. Based on your last thousand tweets (or those of someone you're interested in knowing a deeper understanding of), TweetPsych builds a psychological profile, indicating a score and in some cases an interpretation of your score within various cognitive or emotional parameters. It also displays a list of similarly scored Twitter users who have been analyzed by the TweetPsych service. The assumption here being you would want to know (or at least "follow") other Twitterers that think like you.
It's an interesting idea, but the accuracy of the still beta service is open to debate. For example, I was unaware that GeekTech is known to use many metaphors in its tweets. Nor do I agree that PCWorld often tweets about "various cognitive processes like learning, thinking, knowing, etc." Then again, maybe TweetPsych holds a deeper understanding of GeekTech and PCWorld than I could ever hope to comprehend. How accurate is your TweetPsych profile?
Speaking of which, why don't you follow GeekTech on Twitter if you're not already.