[EricH]

Official hints began for the 2003 season, Stack Attack, IIRC.

2003: the quadratic formula, used as the scoring formula. (not quite sure if that was official or unofficial via Dave's signature)
2004: Lines from the song, "Stairway to Heaven". (Same note as 2003)
2005: Riddle.
2006: Riddle.
2007: Picture of a scored game piece--up close, so only the inside edge of the game piece and the diamond-plate circle with the number 5 on it showed.
2008: 3 hints: IR receiver board, GPS coordinates of the Tortoise and Hare statue in Boston, and "Vets Hurdling First Tetras", which was an anagram of the password to the manual, minus punctuation.
2009: First a picture of an opah, or moonfish, then a riddle.
2010: 2 CAD models of field parts
2011: See hint thread; reversed album cover.

Fakes: Various rumors that turned out not to be true, but there is one classic one that was fairly close in some aspects: A leak was claimed before the 2001 game.
Greg Needel's hoaxes were the sort of "it's out! Ha, ha, fooled you"; 2009/2010.

Lavery red herrings: Numerous. Random sayings, faked pictures, comments about whack the Billfred being the game, you name it. Epic red herring was the morse-code signature spacing for the 2010 season. And yes, some herrings are red when Dave posts them. Typically 3-4 or more per season.