RA  rockets all the way baby.
kill the man with the skull ( the guy himself cant fire a weapon )
1fctf
overload
harvester
 double domination

hmm, a headhunter style game mode where you have to grab the heads of your victims to score might be fun, specially if they bounce and roll and take knockback from weapons

"Kill the carrier" might be fun, but what's he gonna have? One of the little green googly things from keen1? Or better yet, he'll be carrying a screaming, glowing LSoV.. That would work..

Capture and hold would ROCK, I remember that from 'ol Team Fortress for Quake

hmm, more ideas..

Countdown: Players start out fully loaded, and the closer they get to the fraglimit, the fewer weapons they have, until they've got to do it melee-style.

Single Flag CTF is an interesting thought, but the flag room normally gets camped.. unless you could set up a random spawn for the flag... hmm...  

I don't know how this one would be done, but a mode where you receive say a random weapon every X seconds and maybe a random powerup every X seconds would be cool..

And I'd honestly love to see an objective-based attack/defend mode.. Like.. guh, what was that called in UT..? Assault? That would rock.. It'd require some new map entities, but it would rock .

But 'Catch the pointy-eared-alien-bunny-thing' wouldn't be foxxable

foxable material there, I don't think a yoda model will fly .

But like I said, I think a glowing screaming LSoV would work..

it'd be amusing, specially if you had a team-based version where they've got to defend the guy carrying it

Or actually, that would be an interesting idea for a single-flag-ctf style game.. find and return.. and of course it'll be obvious who's got the item that's getting returned to base for a score..