FPS Playback Demo Links
Doom/Doom2  (note: many sites are both sp and dm)
The Compet-N // Forum //  http://competn.doom2.net/
Classic Doom -- Ledmeister
Doomworld Forums // Demos Forum // Demos Forum more
Public Doom Archive of the Non-Gods -- Slagboom / Schreivogel / Ratcliff
Doomed Speed Demos Archive // TAS -- Opulent
e6y -- Andrey Budko -- tools-assisted
Tools Assisted Demos -- The original TAS site -- Yonatan Donner, Esko Koskimaa, and Peo Sjoblom.
http://www.visionsofdoom.us/ - Andy Olivera
http://czech-n.czweb.org/news.php?cat.2
Jason Henry
Grazza
Yonatan Donner
Karthik Abhiram
Magikal
Doomworld walkthroughs
http://www.czech-n.wz.cz/czech-n.php - Czech-N

-- deathmatch
Doom2.net -- BahdKo
   Recordings
   The Doom2 Deathmatch Alliance
Doom 3 Croatia
DevastatioN's Doom2 Homepage
MykDoom -- Myk Helnyte
Fimus' DoomII Page
Badfish Zdaemon
Clan Acid
http://tokeserv.ath.cx:81/zdo/ - Toke
CHTV- zdaemon - Mogul
CHTV - doom2
Stuart 'Yeti' McKendrick
Jason Yasuko
Doomaniax
Predators
Door to Hell
http://www.gamezone.cz/ZaznamyHer.asp?H=30
Cycloid's demos and wads

Heretic / Hexen
Heretic-N -- Vincent Catalaa
DSDA - Heretic/Hexen
 

Major/Multiple FPS demo sites / Clans
Cyberfight
Clanbase
Challenge-tv // Challenge Smackdown
Sean 'Cache' Shelton
Esreality
Gotfrag -- login req.
Eyeballers
Schroet Kommando -- login required // also has registered-only files.
Against All Authority
Mortal Teamwork
Team 3d -- login req.
http://www.mouz.de -- Mouseports HL-CS
http://speeddemosarchive.com

Quake/Quakeworld
http://speeddemosarchive.com/quake/
http://www.challenge-tv.com
http://www.quakeworld.ru/demos.:)
http://quakeworld.us/demos/
http://nqr-network.com/nqr9/

Quake Speed Demos Archive // Quake Done Quick
Nation's Quake Rank
http://www.quakeworld.ru
   http://duelmania.quakeworld.nu
   International Quakeworld Bot Challenge 2004
   Quakeworld World Champions 2004
Custom Duel Map Tournament
Underworldfan
Ill Mind Moves -- Nagasaki (requires js)
http://demo.qhlan.org
http://www.daddied.com/demos
German Quakeworld League
Methos Quake
Vondur
Team Shambler
Windlash
Spores Den
Blueyonder
http://www.quakeworld.nu
http://gibbage.mine.nu
http://koti.mbnet.fi/qwta/

Quake2
http://q2scene.net/ds/ // http://kubus.rulez.pl/~claymore/q2/ds/index.php?op=d1&id=4
http://www.tastyspleen.net/
http://www.clanbase.com/demolist.php
http://quake2.com.ru/files/tdm/

Demo Squad // DS -- Claymore
Q2players - Outbreak
http://skene.arenanet.fi/ // demos // Invitational Spring 2004
Belgian Quake2 Scene
Nordic Quake League 2 Part 2
Savage CTF Demos
Dye.ssau.ru
You
International Champions Compete
Clan HOR
Clan Noll8
Revilla
Qa'spel's Quake2 Training Demos
Observer Mode
Cleaner Wolf
DooWah's Blue Hue Q2
RocketArena2
http://www.q2central.com
http://www.kapitanq2.prv.pl
http://inthevoid.com/va/
http://gibbus.servequake.com / ftp://visitor:gibbus@gibbus.servequake.com:6666

Quake3Arena
http://www.esreality.com / movies
http://www.cyberfight.ru

Quake3DoneQuick - Bot Challenge
Static
http://www.q3acn.com

Half-life
http://demos.thecpl.com/
http://www.team3d.net./
http://www.gotfrag.com/
Schroet Kommando
http://www.esl-europe.net/eu/download/

http://redrum-hl.com -- HL-DM Steam 1.6 demos
http://www.csgn.co.uk //  http://www.csgn.co.uk/movies.asp -- hltv crap
 

OLD links:
-- single-player
The COMPET-N // Compet-N // Competn.doom2.net -- Adam Hegyi / Bahdko
Mirra -- Dashiva / Xit Vono
Russian Doom site
ftp://3darchives.in-span.net/pub/idgames/lmps/  -- old ftp.cdrom.com archives -- dm/sp
Doomworld Demo Forum // demos -- messy mix of 2004 demos
Visions of Doom -- Andy Olivera
Doomzone
Alexis Neuhaus
Ilkka 'Mineral' Kurkela
Brad 'Vorpal' Spencer
Brian Lewis
 
 

6/2004 - updated 8/2006 -- Opulent
So many have disappeared or are currently offline. Some of these are OLD but still online. This is not a complete list, but it should get you started.