Powerful 3D engine that combines indoor BSP and outdoor terrain levels. Includes Windows based tools and editors using DirectX 8's latest features. [Commercial, w/ demo] http://www.powerrender.com/
Provides a comprehensive list of 3D engines and their features, along with reviews, ratings, and screenshots of each engine. http://www.devmaster.net/engines/
A 3D game engine written in and for Java. Many features including collisions, particle systems, shaders, terrain system, renderer abstraction. http://www.jmonkeyengine.com