So, we all know that FF9 references the previous Final Fantasy games. Let's list them I won't list the obvious ones.

-Rufus's welcome ceremony is playing during one of the first Active Time Events after the Prima Vista crashes at the begining of the game. (FFVII)

-Vivi is dressed like a traditional black mage (FFI)

-Garland was a villian in FFI (FFI)

-Garnet wears the tradional white mage robe for part of the game. (FFI)

-When the characters go to the new world, it's almost identical to when the characters in V when to the new world. (FFV)

-Terra is a reference to Terra from FFVI (FFVI)

-Zidane and Beatrix are loosely based off of Locke and Celes (FFVI)


List more

The line "No cloud, no squall shall hinder us" in the play at the end of the game referring to the previous two games' protagonists Cloud and Squall

Zidane looking at a large sword in the weapons shop in Lindblum: "I used to know a guy with spiky hair who carried a sword like this..." - who else but Cloud XD (FFVII)

In Dali, Stiener goes into an pub and says when he finds out it is closed, "Pubs are supposed to be a good source of information."

just like earlier FF games.

Thats cool, I've played FF9 multiple times, but i never noticed these things, I should pay more attention >.<

Oh there are several more. IX is full of references to previous games.

I think Namingway was mentioned at some point which is a reference to IV where Namingway is the guy that will change your characters name if you wish.

You also start out with a Knight, a thief, a white mage and a black mage which is the most common party for FFI and I think the default.

To add to the whole Garland stuff mentioned by Rydia, it is said in the game (by Mikoto I think) that Garland once tried to take control of the cycle of souls by force but failed. Presumably a reference to FFI.

FFI also had a Mount Gulg, and FFIX has Mount Gulug.

The design of the characters hails back to the originals of the series. Not only Garnet's quintessential red indent white mage cloak and Vivi's blue coat with a yellow pointed hat - the choice to populate the world with SD characters refers to sprite designs, in opposition with the more contemporary full-scale designs.

The Four Fiends from the original game make a comeback in IX.

The story you have to put together for Ramuh to join you is about an early part of FFII when you go to the Ice Caverns with Joseph.

There are Tetra Master cards of Namingway and the Enterprise from FFIV.

Fat Chocobo from FFIII and FFIV makes a comeback.

There are LOADS more....

The Rat Tail you can buy in the auction house is the item you need to prove to Bahamut your worth to advance classes.

Une's Mirror and Doga's Atifcat.
The FF3 god/mage things I can't remember to well. But defo link there.