well lets my biggest ones would be:

-beating emerald weapon on accident while watching a porn
-attacking ruby weapon twice, going out making a sandwich, coming back and having it dead
-2 gold chocobos
-2 of every summon at least
- not getting it once aganist sephiroth

thats about it that i can think of. iv never had my characters up to lvl 99 before in 7.i beat the game in the 60s or 70s.

Accomplishments? My first playthrough I completely missed both Yuffie and Vincent. I was over level 50 when I went to get Vincent...basically killed the Lost Number in 2 regular hits.

It took me a very long time to beat the One Winged Angel. Granted, I didn't try every day...when I'm that stuck with battles (usually final ones), I leave it alone for a while until I feel like dying again. I was just lucky once and voila.

One of my fondest memory goes back to before I knew how Limits worked during one of my first playthroughs. I managed to get Barret's Ungarmax before Wutai when Yuffie stole all your stuff. The RAPPS flying boss went like this:

Cloud-> attacks
Cid-> attacks
Barret-> attacks
RAPPS-> attacks Barret
Barret-> LIMIT BREAK! UNGARMAX!
RAPPS- *death*

It was hilarious.

Ive beat the game a few times and beaten ruby weapon, all level 99 all ultimate weapons all that jazz, all master materias (you can actually get those kind of easily if you get them from bueghengen in CCanyon, never breeded any chocobos but i will in the game i am playing now, never bothered with emerald weapon, by the way i dont know if you knew this but you can replinish you chocobos stamina constantly if you hold down r1 and r2 while it runs....

-Most of my characters are in the high 80's to mid 90's.
-Have beaten Rudy Weapon and he never even hit me in battle.
-Have every single piece of Materia.
-Teamed up with Indiana Jones to raid the sunken Ship and find the Hades Summon and Morph the Underwater Materia junk.
-Have spent close to 100 hours of gameplay in the game.

I have everyone's ultimate weapons and limit breaks, have most of the materia, did the chocobo, sunken gelnika, and Wutai sidequests, and beaten all of the weapons (including Emerald and Ruby). My characters are on level 80.

Maxed gil, all chocobo's breed that I could possibly fit in the stables. Learned everyone's level 3 limites before leaving midgar, beat all weapons, and solo'd Safer Sephiroth with Cloud(killing off the other two on purpose). Maxed out Cloud's str and vit stat. It got to a point where I didn't need materia on him anymore.