Since I'm new here, might as well share my renames...
I was 11 when I played the game the first time, so I hadn't renamed anyone. Only nowadays that I play it again (and reeeeeaaaaaaally slowly), I decided I'd have fun with this.
Cloud - Spiky (Unimaginative, but the funniest part is that Barret never insults him with this nickname anymore... he calls him by name!)
Barret - Ecologist (Because he is.)
Tifa - Goddess (DUH)
Aeris/th - Barbie (It's the pink. On the other hand, seeing the phrase "Barbie is dead!", leaves me in glee...)
Red XIII - Gentleman (It's the way he talks.)
Caith Sith - Meow (I know...
)
Yuffie - Woof (Her name does sound like it!)
Vincent - Alucard (
)
Cid - Smoky (Unimaginative as well... bah.)