This devious bug came anonymously, and is worthing of an award for its
deviousness and usefulness. (To any would-be-impostors: I know the email
address, so don't even try.)

One bug I remember is with the crystal ball item. You could think
about a player and look at the ball and to show you the room, the ball
would transport you there and back instantly. So if you sheltered
where you started, and then used it, it couldn't move you back and you
could transport to anywhere in the game, such as the reinc room (past
the step where it removed your skills/spells). Then you could join
another guild and have all your old skills/spells.