Aussie Pythons forum - Users discuss what kind of substrate they prefer to use in their snake enclosures.
Naturalistic vs. Sterile Enclosures
Reptile Channel - Users discuss whether they prefer naturalistic displays or sterile enclosures for their reptiles.@ Reptile Channel
Captive Bred Reptile Forums UK - Users discuss how to set up naturalistic vivariums with bioactive substrate.
Geckos Unlimited - An older thread definitely worth looking at, where a user shares photos and construction information about the amazing naturalistic vivarium that she built for her leopard geckos.
GeckoForums.net - Members discuss the pros and cons of not using any form of substrate in leopard gecko enclosures.
Tortoiseinfo.org - Members share pictures and discuss various options for tortoise hatchling enclosures kept outdoors.