The just-for-fun prestige class conventioneer (or, if that doesn't work for you, here) that was posted on Wizards of the Coast Web site in 2001 possesses the special ability convention savvy. The special ability allows a conventioneer to pick, among others, the specialty obscure knowledge, that, in part, says, "Conventioneers know things like which image in the Dungeon Master's Guide has shown up in all three editions."
Bonus: The article's About the Author section lists as one of Matt Smith's possessions a picture of Torg waving "Hi." Who or what is Torg? Or is this a Matt Smith inside joke thing? (Note that this is likely unrelated to the Torg role-playing game—that'd be one weird picture—and that the author is probably not this nor that Matt Smith—although I'm sure the author's a great guy, too.)