WinRAR:

Use this to uncompress files that are in rar, or zip format.

Sonic Adventure DX:

Modeling:

Misfit Model 3D

This is a good (and free) modeling software that can be used for SADX.

SADX Modeling Tools Pack

A pack containing tools that are necessary to model in SADX and it includes Zarosguth's SADX Model Notes.

Hex Workshop

This is the recommended hex editor for all SADX hacking. Please note that this release is 100% legal because it's an older version of Hex Workshop than version 6.

Hex Edit

This is a Hex Editor that can be used to find a byte's value while hexing a model. I'd only recommend it for this, however and the rest for HxD.

PVM Editing:

PVMedit:

Use this to open SADX's PVM files and edit them. Check the tutorials section for how to use it.

BGM and Sound:

Switch Sound File Converter:

Use this to convert MP3 and other sound files to wma and wav for music and sound effect hacks in SADX.

SADX Sound Effects Hacking Pack:

Use these programs to uncompress and compress the DAT files that SADX uses for it's sound effects.

Sonic Heroes:

Sonic Heroes Charrepper:

Use this to replace characters' animations and models in Sonic Heroes without the game crashing

TXD Workshop:

Like the PVMedit for Sonic Heroes. Use this to open and edit Sonic Heroes' TXD files.