Thoughtstream by Boxed Thoughts.

From the website:

Boxedthoughts is a collection of thoughts posted by anonymous users. Together, these thoughts form a stream of thought, or a thoughtstream. The thoughtstream represents the flow of thought or thoughts that embodies humanity.

Thoughtstream is policed by (you guessed it) the Thought Police, who deletes spam and obscenity. You can see also pure (unmoderated) thoughtstreams and deleted ones. There are gems there….

Link – via Bifurcated Rivets