The Cutting Room FloorHoly stuff, this website is really interesting, it documents the lot of stuff that were cut out of games before their release, and also prototypes and things they simply programmed but never used in the games.
For example, here are a few highlights from their pokemon sections.
Pokemon Red & Blue
Did you know the pokedex order was going to be much, much more different in Red and blue?

That by default, in the U.S version of the game, the names for the player and rival are "Ninten" and "Sony" , and can be used by skipping the name selection dialog via cheats?[/url]
Pokemon Gold & SilverDid you know that a lot of the sprites were changed for international localization?
That the game was originally going to have it's own safari zone, that is still in the game's code but inaccessible?

That the developers left the early maps for the towns in the code?