This is dangerously addictive! I'd love to see decorative elements like statues and fountains, as well as flowers and such. Maybe lava for volcanos. I had fun figuring out how the various elements would interact with one another.
Edit: How did you get the blue church in Example World IV? Or is that only in the DL version? (Which I can't play because I have a Mac.) Nvm, I figured it out.