This is for Minecraft 1.2.4 and 1.2.5. I didn't made this but i posted this to help you if you don't know how to instal!

How to instal:
1. get a win rar (easy way)
2.open TooManyItems mod
3.open start menu and type in: %appdata%/.minecraft
and select minecraft
4.open bin and and open Minecraft.jar (right click-> open with->Win rar)
5.then drag all files from TooManyItems mod to Minecraft.jar
6.DELETE META-INF or the mod won't work!
7.close it and you are done!

So now im gona tell you what you can do with this mod:
1.you have a lot of items in inventory beside the main inventory
2.you can change your gamemode from survival to creative and other way around
3.you can change time
4.you can save your build

INPORTANT: IT DOES NOT WORK IN MULTIPLAYER