Hi. This is the main topic of modding tools. Modding tools will be added to this list so it can be easy to find.

HxD:
Hex editor, used for basically everything in modding.
Download Link

CPK Unpacker:
Used to unpack .CPK files.
Download Link

CPK Repacker:
Used to repack folders and files to .CPK.
Download Link

Noesis
Basic model viewer for any Storm game.
Download Link

HCA Decoder:
A little tool that converts Storm 4 voice and sound files (.hca) to .wav:
Download Link

Storm 1 and Storm 2 Audio Converter:
This is a pack with VGSC and NUBExt, that can be used to convert S1 and S2 audio files to .wav files.
Download Link

PES File Editor:
Used for music modding.
Download Link

Scaleform Video Encoder
Used to convert Storm 4 .usm cutscene files to .avi and viceversa.
Download Link

Ombu's S4 File Size Tool
An automatic way to fix the file-sizes in your Storm 4 prms.
Youtube Link

Ombu's Revolution File Size Tool
An automatic way to fix the file-sizes in your Revolution prms.
Youtube Link

Texmod
Everyone knows Texmod, though only noobs/lazies use it.
ONLY WORKS FOR STORM 3 + REVOLUTION.
Download Link

Opentpf
Decrypts and Packs the textures from a texmod file to a .zip
Perfect for Porting onto Storm 4 (or even S3/Rev)
Download Link

Byte Blaster Byte Remover
This neat little program is able to easily remove those headers of byte from Texture Files, be it PNG or DDS.
Download Link

Mesh Swapper V1.0 by lyingcake77
Swaps meshes automatically (doesn't work for meshes with different file sizes at the moment such as eyes, some weapons, etc)
Download Link