Randall Monroe of webcomic XKCD came up with a great idea for reducing the noise in the XKCD IRC channel: filter out all sentences that have been spoken in the past. A moderator bot scans two years worth of chat logs and blocks any repeated statements, forcing chatters to come up with original thoughts and avoid the repetitive greetings, acronyms, and in-jokes that make up much of the noise in a chatroom.