[Flaser]

Pretty self-explanatory title.
This is for coders to list each and every single feature.
This could be the first step in familiarizing everyone with them, and could act as a backbone/reference for the wiki.

[Goober5000]

...

Well good luck with that.  I think you'd be better off encouraging people to update the Wiki.

(BTW a Wiki upgrade is in progress, so you'd be even better off waiting for that first.)

[Flaser]

OK this will be the bare bones I can think of until I have the time/connection to take the dive:

Graphics:

In-game
Geometry
Hardware Transformation & Lighting (OGL/DirectX 8)
LODs*
Superdetail boxes (distance based subobject rendering)
Skyglobes/Skyboxes

Texture Formats
TGA, JPEG support as textures, ANIs as textures
'32-bit PCX' support (each PCX has its own palette)
DDS support
EFF container format to replace ANIs

Mapping
Diffuse mapping*
Glow mapping
Specular mapping
Environmental mapping
Mipmapping

Particles
Advanced Particle Rendering
Particle Based Thrusters
Lensflares

Interface
PCX-32 support
Scene design support

Sound:
OGG support
OpenAl implementation
Simulated Speech

Gameplay:
Dumbfire Indicator
Strafing enabled/mappable for players
Orbradar
Fighterbeams, Ballistic Primaries, Swarm, SSM, .... and more weapon modes

Design/FREDing:
MOD-support
AVI-cutscene support
Dynamic Tables
Multispecies support
Multiship Docking
Permanent Variables
Gazillion of FRED Sexp additions

[Inquisitor]

There is a whole readme as well...

[Grug]

Scene Design Support? o.O

[Goober5000]

I think that's cutscenes.

Anyway I'm closing this.  Documentation should be in the readme or the Wiki, both of which are in the process of being upgraded.  Having it in the forum is just messy.