Well listen here, I have a major rumor or two:

1} This is totally unproven but yopu can get Cid's car!!!!!! What you have to do is, keep Cid in your group at ALL times, and in disk 2 go to the item shop in the slums. He asks for and gets the car parts. Then take them to his garage to tune up his car. This unlocks secret areas in the Highwind also.
UNPROVEN


2} Cid has a better Ultimate Weapon. Get 5000 + points in the roller coaster laser game to get this weapon. It has materia growth also. The weapon is the flayer.
PROVEN

{3}Secret Character:
You may have heard this 1000 times, but i have an uncle working for Squaresoft USA And i have information on how to get a secret character. Zack. Remember the man Cloud mixed his identity with? Zack. Who's Cloud's best friend? Zack. Who saved Cloud from Nibelheim and brought him to Midgar? Zack. Well, here's how to get him. 1st, in Midgar, you must answer EVERY question CORREXTLY! It must be done in a certain way. Now, before starting the Kalm flashback, if you answered correctly, you will hear Aeris say Cloud reminds her of a man she once dated. After the flashback, Cloud, Tifa, and Aeris stay in the Inn, and Tifa mentions something about a man she found half-dead outside of Midgar. Now continue the game as usual. At the Temple of the Ancients, you'll find Zack killed by Sephiroth, and he'll enter the lifestream. Now get up to the 3rd CD. Go to the Gongaga reactor, and bring a Super Sweeper and a Mutsurame Blade( both Gold Saucer Shooting Coaster prizes ) and use the Sweeper on the reactor. It will explode, and then use the Blade. You colapse and find yourself hearing Aeris's voice, then you wake up, and find yourself next to Zack. You talk for a while, and he leaves. You meet up with him again the North Crater. Then he is able to join your party, and starts at level77. Can't say much more about it, except, he's a great character to have!!! Submission: Matt (Master9360@AOL.com)
If you prove or discredit any of these, Please Let Me Know