Modifications and Add-Ons

AntiShockHo
Server administrators' anti-cheat modification which detects cheat keybinds and actors.
http://www.catchersctf.com/AntiShockHo/

CombatMaps.de
Contains map and mutator reviews, maps of severals different types, official files, tools, sounds, textures, and hacks.
http://www.combatmaps.de/

Eavy's Unreal Tournament Mods
Downloads and information on a range of mods and mutators made by Eavy.
http://eavy.beyondunreal.com/

GF-REX's Unreal Addiction
Collection of maps and mods designed for Unreal Tournament. The site contains many maps and a few modifications.
http://www.racertech.net/rex/

Infiltration
Military-style modification.
http://infiltration.sentrystudios.net/

Marathon: Resurrection
Total conversion of Bungie's Marathon series video game.
http://resurrection.bungie.org/

PlanetJailbreak
Team-based modification where one must kill opponents to put them in jail.
http://jailbreak.beyondunreal.com/

Strontium Dog: Unreal Tournament
News, images and information chronicling the creation of a series of Strontium Dog themed add-ons for Unreal Tournament.
http://www.strontiumdog.pwp.blueyonder.co.uk/

Unreal Tournament Map Rating
Offers user-created maps with reviews. Also offers user ratings.
http://www.utmr.dk/