This place is to help you learn on creating mods and the tools you need.
First off lets start with the complete tutorials.

Visit our mod making forum!

Essentials

MPQ 2k - this is pretty much the only tool out there thats lets you put files back into the mpq's. This has been updated with a slew of new features.
D2 MPQ Extractor - the tool you need ot extract files from the mpq files so you can make your own mods. This has been updated to work with the expansion and all of its wonders.
D2 Mod Installer 1.1 - a program I created to be used with making your mods work with end users. This is for the mod developer. It contains complete tutorials on setting up and releasing your mod. I will not post mods on this site until you use this tool, it allows you to create mods which work on all versions of the game. This latest version backups your files and saves your diablo 2 directory as well as fixes any directory path's that were getting messed up.

Tutorials

How to make mods for Diablo 2: LOD!

Choas Mod Creation Kit! - a nice kit a little outdated but the one everyone learned to first create mods.

Lighty Mod Creation Kit .05 - an really up to date kit created by lighty detailing how to use everything with all the tools you need included.

Next its time for the basic tools you need.

Mod Tools
This tools are what you need to manage the files.

DC6 Converter - the tool you need to convert dc6 images to and from.
PSI DC6 Converter - a converter like the one above but much easier to use and simpler interface.
MPQ CV5 Image Viewer Extractor - this is really nice for easily browsing your mods without have to actually extract the files from the mpq first.

Mod Editing
This is the section where you get to download the tools you need to EASILY edit and create your mods.

Unique Items Editor 0.91e - this lets you edit the unique items when making your own mods.
Tab Text Utility - The app loads tab-delimited text files used by Diablo II in the data mpq files.
TBL Editor 1.02 - This lets you edit those tbl files found in the diablo 2 mpq files.
Skill Maker 0.87- This awesome tool lets you create skills for mod making and more.
Mod Editor 3.0 - Lets you create your own mods with clicks of buttons.
D2 Mod Editor .04 - another editor to create your own mods. You can now edit the Unique, Magic and gems items.

Other Sites
Phrozen Keep


Visit our mod making forum! Its very helpfull and can be used as a resource as well as more.