3D Programs
Blender
Blender is a 100% free 3D moddaling/scripting/textering program. Infact, it is rather powerfull, with full games and animated moives being made in it to show off what you can do.
http://www.blender.org/
Texture/Pic Edit Programs
The Gimp
The Gimp is a free Photoshop like program. It is a bit differnt in how it dise some things, but it is a very powerfull tool once you know how to use it.
http://www.gimp.org/
NifSkope
Texture editor for .nif files (Thanks to Chaka ZG for the link)
http://niftools.sourceforge.net/wiki/NifSkope
MapZone
Procedule Texture Genarator. (Thanks to TheMagician for the link)
http://www.truancyfactory.com/portals/mapzone/mapzoneIndex.html
Plugins
Gimp DDS
This is a plugin for GIMP version 2.6.x. It allows you to load and save images in the Direct Draw Surface (DDS) format. (ThanksBwillb for the link)
http://code.google.com/p/gimp-dds/
Any more to add to the list? Post it with a link and what it dose. XD

