You left out one of the best mods ever.
Return to Castle Wolfenstein : Enemy Territory.
This was a multi-player mod for the new version of the original FPS.
It assigned classes that each had a specific job.
Medic - obviously to heal teammates, but could also heal self.
Lieutenant - distribute ammo and call air strikes.
Soldier - had all of the best weapons like flame throwers and rocket launchers.
Covert Ops - sniper that can spot enemy landmines and units to display on the team minimap.
Engineer - could plant dynamite to blow objectives and landmines to blow the enemy.
These are all good mods, but I think they missed one of the best ones I have seen.
Star Wars mod using battlefield 2142. You can play in space in a tie figher or xwing attaching huge star destroyers. You can play as rebel or alliance on the ground. Its pretty cool and everyone here should check it out if you have Battlefield 2142.
These were my favorite mods:
1. Capture the Flag for Quake 1
2. Team Fortress for Quake 1
3. Counter-Strike for Half-Life 1
4. Rocket Arena for Quake 1
5. Head Hunters for Quake 1 (Not mentioned here but it was tons of fun and didn't get the attention it deserved)
6. Future VS Fantasy for Quake 1 (My friend and I always played co-op as the ninjas)
7. Reaper bot for Quake 1 (Not really a favorite but it was definitely a milestone for single player deathmatch)
I hightly recommend Red Orchestra for those who don't know it and look for a real challenge. Great game, great community... Their games usually have tones of content updates, new guns, maps, vehicle...
call me lame, but I like the Annihilation Mod for the original Tribes.
I also played a lot of Killer Quake
The original counter strike was fun until it because Hacker Strike, I also didn't like the 1 shot 1 kill with the AWP.
For UT I think it was Chaos Mod that gave you a huge rocket you can ride on and control. The Love Rocket I believe it was called.
Who was the editor for this list and why did s/he let this go to print with such a narrow selection of games (Quake, anyone?) and genres (anyone at Tom's play RPGs?). The point is that RPGs are probably more heavily modded than any other genre. Bethesda's Elder Scroll series and the Interplay/Bethesda line of Fallout games come to mind as do EA's games, most recently Dragon Age and it's progeny. How about taking a poll? I'll bet it would create considerable buzz and produce a more representative list of mods.