I think I'm going to play around with shaders next. I just got OpenGL Shading Language (the orange book) and I've been dying to play around with shader programming. I got this book a month ago and it was really hard to document the terrain rendering code while this book was sitting on my desk taunting me: "Come on... you know you want to play around with nice, colorful, candy-like shaders, eh? You don't need to document code. Come have fun, mwa-ha-ha!"
When I feel like developing my terrain engine again, I'm going to create a new renderer. I've got a lot of ideas in improving what I got after getting some ideas by thumbing through OpenGL Shading Language.
Right now, this is what the OpenGL 1.1 renderer can do without using textures or shaders:
This image is taken from the south end of Valhalla Provincial Park, looking south.
I can't wait! Shader programming looks like fun!