dtgreene: Bugs that, in some cases, enhance the gameplay. (Yes, this does happen.)
I am currently playing SaGa 1 (Final Fantasy Legend 1) with a solo esper (mutant) and somehow reached 99 STR before 99 MANA. Fourth world, and this happens:
In the tower, the strange man says "Nothing works against su-zaku. You can only run." Well, it just so happens that the game gives you a SAW in the segment of the tower leading up to this world, and said saw works on the random Su-Zaku encounters. Take that, invincible foe! (Too bad it doesn't let me equip the entire world, but then again skipping the world would mean skipping the BAND which blocks most things.)
One other little thing (that is unfortunately not present in this game): When the game accounts for killing enemies you aren't supposed to be able to. Lufia: The Legend Returns does this a lot. Of course, the first of those bosses (actually the first boss in the game) is so difficult that you will see the quote "THIS is what I would call frue [sic] destuction" a lot when trying to kill him, as it's only barely possible to do so before he nukes your party.
I managed to kill Anna Winslow, the ghost in Fallout 2. You just have to use the revolver and roll a high enough critical. Things like that stick with you so I agree on that one. :)