Whether you're a big fan of floatation tanks or are just mildly curious, you're going to have a lot of fun with this resource that I just found - http://amaznode.fladdict.net. Type a search term into the field where it says "Input keyword here." and hang out for a minute or two while an interconnected web of books and videos with relevant material is created.

I put in the search term "floatation tank" and was given many book results I'd never heard of. The graphical interface is very eye-catching and the number of results that can fit on a single page is very impressive. Highly recommended.