GameWinners - http://www.gamewinners.com/gamecube/MarioKartDoubleDash.htm Provides secrets, hints, and time trial records.
Mario Kart Time Trials - http://uk.geocities.com/josh_rocks_03/ Information, tips, and time trial records.
UnderGroundOnline - http://cheats.ugo.com/cheatdisplay.php?gameid=20156 Includes a selection of secrets and unlockable bonuses.
