Worth sharing this I guess
.dds
Direct Draw Surface files are used for pretty much most of the textures for the models in game. The best place for the tools you need (including the plug-in for PhotoShop and PaintShopPro which adds native .dds file support) is this link;-
http://developer.nvidia.com/view.asp...ression_plugin
Theres a neat installer there which adds thumbnail view to Explorer for .dds files
.tga
Your decent image editing program should be able to handle this - most ingame images (texture/image maps) are in this format.
.wnd
Hopefully the 'official' WYSIWYG editor (GUIEdit) will come out, but if not and youre really desperate you can edit these files in WordPad although you need to know what you are doing (this is how some people have enabled things like the clock on the main menu screen).
.ini, .txt
WordPad - use WordPad. Do not underestimate the power of WordPad.
.map
Need WorldBuilder. Did I mention you could use WordPad to view some obscure stuff?
.w3d
Oddly enough, the Renegade modding tools (gmax with Renegade gamepack) will do for now.
.bik
RadGameTools - as per RA2.
http://www.radgametools.com/
.csf/.str
Use Olafs string editor or if all else fails use WordPad (some versions are readable, some are not).
.big
Use MultiEx Commander to extract from these files -
http://www.xentax.com/html/multiex-downloads2.htm
ADDENDUM:-
.m3d & .flt
3D animation files (.m3d) and filters (.flt) - Corel Motion
I wont insult you by saying how you can edit .wav (IMA ADPCM) and .mp3 files.