Ckef Worx
A beautiful Flash site with great animations and kicking beats. More importantly its the headquarters for all of Ckefs RCT3 custom content including his popular Rockslide Lagoon Set.
ImaginationEntertainments
Currently down for maintainance, Imagination Entertainments is managed by the incomparable Shaun, known across the community as the creator of the Imagine Sets.
Revolutionary Rides
The #1 custom flat and tracked ride creators. Follow Revolutionary Rides as they modify the game beyond our own imaginations, you can also find links to the most up-to-date utilities for custom content in RCT3!
Meganaut
Meganaut by Moby. Home of ePark and the best place to find all of Moby's custom scenery sets and videos!
A Hint Of Spice
The master of texture and the god of vegitation himself. Old Spice's site features downloads for all of his beautiful sets and more importantly his inovative work in custom pools and paths.
Shyguy's World
Community Forums, Custom Scenery, Park Discussion, not to mention home to both the "Complete List" and the "Showdown" competition series. What more do you want?