I stumbled across marginalia.nu, a search engine designed to index smaller websites on the Internet. Here's a few sites I found with their 'random' button.
bogleech.com - "Creature design reviews, bizarre biology, weird fiction and year-round Halloween horror since 2001!" It's a website about monsters, and they really go in depth about them! Video games, movies, etc, ranking their favorite This is what the Internet was designed for: to go REALLY DEEP on a random thing like monsters in media. .
planetfuraha.nl - A fantasy planet and some of the life-forms on it. It's a fan-fiction project, like a smaller independent version of the SCP project.
antbase.net - A website about ants. All of the different kinds of ants. Where they live. How they differ. Why? I'm not sure! But ants are pretty interesting once you go off the deep end...What will you find?