Below are some sites that are worth taking a look at. Note: I'm happy to trade links with people, but if you ask to trade links and then you de-link me, I'll have to remove your link as well.

Fantasy's Realm
A nice site for RPG material and a variety of other topics.

ImagineAges
Home of Canada's greatest in-the-works live-action RPG!

Infinityseed World Foundry
A good site for resources and info on creating your own worlds.

ICE Web Page
Makers of Rolemaster, HARP, and a great general-purpose book called Nightmares of Mine.

Karanblade
A cool AD&D site with a variety of goodies (if you don't like the English version, feel free to check out the Porteguese :)

Reaper Miniatures
Best miniatures out there.

Stephen Weir's RPG and Game Sale
Stephen has a variety of gaming materials, from board games to D&D to miniatures, and more! A good site for collectors or other enthusiasts.

Theeurth
Another well-done world for d20/D&D; nice layout, lots of good ideas.

Worlds in the Net
Features links to a number of worlds, rules variants, and other goodies.

World of Erndorth
A nicely-done world for d20/D&D (and I would say that even if they weren't using some of my material).