Where to Find Examples
Ray Casting
Fred (a Wolfenstein-like networked multiplayer game) by USC group. (Requires a Java capable browser.)
Caster for WinG. (Requires Windows 95 or Windows 3.1.)
Id Software has released the source code for Wolfenstein 3D.
A raycasting source code written in QuickBasic.
Java Example
Height Mapping
Caster for WinG. (Requires Windows 95 or Windows 3.1.)
Voxel landscape applet. (Requires a Java capable browser.)
Landscape3D by Jeff Orkin, uses a simplified height mapping technique to render rolling terrain. (Requires a Java capable browser.)
Hozie Doom is a Doom-like engine by Jose Flores, available with source code
.