Chrono Compendium
Has an active community, fan projects, hacking guides, articles, features, scripts, guides, and more! It's the Wal-mart of Chrono Trigger sites! ^_~

Chrono Symphonic ReMix Project
A collection of symphonic remakes of the majority of Chrono Trigger's songs.

Brink of Time: The Chrono Trigger Fanlisting
As the title says, this is a Chrono Trigger fanlisting, and a rather popular one at that.

Chrono Trigger Novel Project
The people here are novelizing Chrono Trigger! Check it out! They also offer fan art, fan fics and various media.

IcyBrian's RPG Page
The ultimate site for RPG fan fics and fan art. Their Chrono Trigger section is vast.

Chrono Trigger Resurrection
This was a project to completely recreate Chrono Trigger in full 3D. From the screen shots and trailer provided, the quality of this remake is of very high quality, what you would expect a PS2 RPG to look like. Unfortunately, Square-Enix found out about it and demanded that they cease the project.

Chrono Trigger @ RPG Classics
RPG Classics' Chrono Trigger shrine. Think of it as a full walkthrough divided up into sections.