In no specific order and not a full list, this we have only added to a bit here and there when we have had time.

All 3D models regardless of program used must be able to export to the Collada format.

Note: The 1.3 patch for Amnesia allows support for FBX formats.

1. Blender - Open-source 3D modeling program that comes with built-in support for Collada.
2. Autodesk Maya - Professional 3D modeling program with OpenCOLLADA plugin support.

1. GIMP - Open-source 2D GNU Image Manipulation Program.
2. Adobe Photoshop - Professional image editing software.

1. Audacity

1. Notepad++: Advanced text editor, crucial for script writing.
2. Geany: An alternative for Notepad++.

Mac OS X alternatives:

1. TextWrangler: A good alternative to Notepad++ on Windows.
2. TextMate: A nice and smooth code editor with many customization options.