Top Links
The best CG and UnrealEd sites on the planet:

3DBuzz Free video training modules for UnrealEd and many popular modelling and texturing packages.

Mastering Unreal Free online courses in UnrealEd and Concept Art.

Unreal/UT Editing Links
Here's a comprehensive list of sites offering UnrealEd tutorials, guides, and reference material.

Fordy's Unreal Site Articles, maps, and some great UED utilities.
Lode's Unreal Definitive tutorials on lighting, movers, and more.
Unrealed.exe A massive compilation of tutorials from beginning to advanced.
Wolf's Unreal A comprehensive series of tutorials and tips.
Rust A massive site devoted to level design for 3D games.
Secrets of the Sages Gamasutra's series of level design articles by some of the best mappers in the industry.
ControlEd Deth An UnrealScript site specializing in player-controlled turrets and cannons.
Unreal Movie Studio Think you're John Woo and Quentin Tarentino rolled into one? Create your own movies using the Unreal engine!

Bothpathing Tutorials

Pathnoding for bots is such an esoteric art that I've devoted a whole section to it. Here's every link I could find. Study them well, and your bots will give even the best players a run for their money.
Unreal Creature Guide A guide to Unreal AI by Steve Polge, Epic's AI programmer.
Unreal Tournament AI Guide Steve Polge's tips for tuning your Unreal Tournament botplay.
Ask the Expert An Unrealized article by Myscha.
Schlacht's Notes More pathnoding tips, with advice on getting bots to navigate stairs properly.
Sutton Pathnoding for Jumpads and Kickers.

Map Review Sites

Think you're ready for some public scrutiny? Then submit your map to one of these sites.

Nali City The original custom map site for Unreal and Unreal Tournament.
UT Booty Hasn't been updated for a year, but there are lots of reviews of older maps here.

General Unreal/UT Sites

General-interest sites for the Unreal and Unreal Tournament community. Map, mods, news, files, patches, and more.

Co30 Clan Site Possibly the biggest and best independent Unreal site on the planet.
Planet Unreal The mother of all Unreal sites.
Unreal Technology Epics Unreal and UT engine site.
Clawfist's Maps The works of Sidney "Clawfist" Rauchberger.
Sinistral's Unreal Maps and a good collection of prefabs.
Unrealism Everything to do with Unreal and UT.
PlanetShane The art of Shane Caudle, Epic's Art Director and creator of many of the Unreal and UT Textures.
Matthijs Maps Maps and custom textures.

Hardware and tweaking

Get the scoop on the latest hardware, and find out how to tune your system for maximum performance.

[H]ardOCP the [H]ardest hardware site of them all.
VoodooExtreme Hardware and drivers, interviews, and general gaming news.
Gamer's Depot Hardware site for gamers.
AnandTech One of the biggest hardware sites on the web.
Hardware-One Hardware news and reviews.
Planet Hardware The name says it all. Part of the Gamespy network.
Sharky Extreme Another good site, featuring a weekly CPU price review.
Speedguide Tweaks to get the most out of your system.
Tweak3D A very good gamer-oriented tweaking site.