The Order of the Stick: An excellent web comic about a party of stick-figure D&D adventurers.

Goblins, Life Through Their Eyes: Another great D&D web comic, largely from the perspective of a group of goblins who feel persecuted by adventurers. Excellent art and story-telling.

Gunnerkrigg Court: An unusual girl goes to a school where strange things happen, and the link between science and magic is studied. This isn't a role-playing comic, but it's really good, so I had to include it.

Girl Genius: A steampunk comic about a girl who has a way with machines.

Looking for Group: A fun web comic based on role-playing games, with a long-running plotline.

Walking in Circles: A barbarian out for revenge hires a mostly incompetent adventuring party to slay a dragon. Good series, and there are puppets.

The Guild: A guild in a World of Warcraft-like game meet each other in person. Good comedy, though the production is weak sometimes, especially at the beginning of each season. Starring Felicia Day, known for her role in Dr Horrible's Sing Along Blog.

D&D PSAs: Funny series about D&D characters talking about themselves. Poor acting but addictive. Basically, just a bunch of college gamers having fun.

Standard Action: Not the best acting, but a fun series anyway, about an incompetent adventuring party. High production value for a web series.

Terra: An anti-social gamer gets sucked into a Final Fantasy-style video game.

Finite Films: Alright. This one isn't gaming related at all, but these people are amazing. Every month for a year, they produced a short film, with constraints submitted by viewers. This is some of the highest quality material I've seen on the web. They deserve to be paid huge amounts of money to make real movies!

Portrait Adoption: You describe your character and state the amount of money you're willing to pay, and freelance artists compete to draw for you.

Liiga: Liiga, a fantasy artist I happen to like.

A faq that tries to answer the question: Is AD&D evil?

Jack Chick: A minister who preaches against D&D. Good for a laugh.

Pokemon - Danger!!!: A funny page, meant to be serious. This web page discusses the evils of Pokemon and its occult implications. Watch out for your children! First Pokemon, then Magic, and then (gasp! No, don't say it!) Dungeons and Dragons!

AD&D Dice Games: Gambling games for various AD&D races, by Desmond Reid.

Simplifying D&D: A troll proposing a simplification of the D&D dice bag.

Usenet Trolls: Why do I find trolls so amusing? I dunno.

Silly Items and Spells

Munchkins: A conversation about a munchkin player who once applied to my D&D game.

Anthologia Dementis, a page by one of the players in my D&D campaign, with a bunch of short stories.