Before Things Go to Hell..

[Jowy]

Depends on the version of the game you're playing. Water Rondo is unobtainable in the World of Ruin unless you're playing FFVI Advance (assuming you picked up Mog that is). Golem and ZoneSeek magicite from the Jidoor auction house can be purchased for a total of 30,000 GP...don't think you can pick those up later on. Seraphim magicite is obtainable in Tzen off to the side in some trees. You can wait on that however and get it for a whopping 10 GP once the World of Ruin hits but it is an exponentially faster way of learning Cure 2. You can only fight Intagnir on Triangle Island in the World of Balance...he's hard as smurf though so I wouldn't recommend it unless you want a full bestiary/rage list. Mailing the letters for the wounded soldier in Mobliz to get your Tintinabar is another. Make sure to have three Mystery Veils, and a Bard's Hat or two in case you feel like building an "unhittable" character or four. Chainsaw from the clock in Zozo.

And don't forget the Atma Weapon in the Sealed Cave!