Halo
Halo2
Halo3
GoldenEye

Number one is easy: Operation Flashpoint

I cant think of any other FPS now :D

Halo, Bioshock, and hold onto your hat: Redsteel. Redsteel not so much for any one thing as the graphics were weak, story was kind of cheesy, and the swordplay was questionable but it really opened my eyes to just how much fun a FPS/TPS using the point and shoot method of the wii-mote can be. I quickly learned to look past the complaints and thoroughly enjoyed the game. If I had to pick one game that I am MOST looking forward to it would be Redsteel 2 (assuming the improve the game).

Goldeneye
Battlefield 2
Gears of War
Battlefield 1942
Doom

I would put the Metroid Prime 1/2/3, but, they are not generally considered FPS in the strict sense.

Unreal Tournament 2004

Goldeneye

Tribes 2

Doom 2

Battlefield 2

close but no cigar

Rainbow 6 : Vegas
Resistance : Fall of Man
Counter Strike
Medal of Honor (first one)

i'll list the most meaningful, since between when i played them and now they become obsolete in many ways:

doom
killing time
goldeneye
perfect dark
black

it's looking like COD4 will be on there soon.

1. CS 1.6
2. BF2
3. Quake 3
4. Unreal Tournament 2004
5. The Dark Forces series. Jedi Knight and all.  

if you count mods

Counter Strike
Natural Selection
Day Of Defeat
Unreal Tourny
Perfect Dark

proves what I said in halo vs bioshock ..multiplayer wins

1. Goldeneye (greatest of all time)

2. Halo (close 2nd)

3. Perfect Dark

4. Wolfenstin

5. Half Life 2

Resistance:FOM
Halo
Goldeneye
Unreal Tournament 2k3
Time Splitters