The Trinity Rendering Engine is made by Andrew Lucas, which contains a lot more features, which are even included in Valve's powerful "Source" Engine. Trinity Render is now being wisely used in most of the mods.
About the fgd file included in sdk and how to use it wisely
A trick using projective shadows in trinity render to produce a good looking shadows
The tutorial showing how to use detail texture system of trinity in your map.
The tutorial showing how to use a HD skybox support feature of Trinity Render.
A tutorial showing how to use Trinity Render in your mod.