I gots some INI tweaks for D3D...I dont use OpenGL but the commands apply for OpenGL too I think.
HighDetailActors - only difference I see is the bullet holes...FALSE makes bullet holes non-exsisting, TRUE does.
UseTripleBuffering - making it FALSE makes ur video card only make 2 passes at the textures...making it TRUE makes ur vid card make 3 runs at doing the textures for more clarity and slows your framerate down.
Coronas - if theres a sun or something, makes u get those round circles in ur eyes..like a circular glare or something
Use32BitTextures - I use FALSE, my TNT gets on its knees on 32bit textures, TRUE is self explanable
UseTrilinear - I use false even though I dunno wtf it is, maybe u can find out and tell me
ShinySurfaces - basiclly gouard shading, makes reflections on metaillic objects I think...something like that, basiclly shading, I use FALSE, when fragging, u wont even notice it..
Thats all I can get for now, Ill reply again if you need modem or multiplayer tweaks...