Kombucha is a pancake-like mushroom and has been used by the Chinese for over 2000 years. It is claimed to lower blood pressure, ease aches and pains, and increase vitality. This guide fully describes what kambucha is and why it grows when placed in tea.
A bit outdated but I liked how it breaks down all the nutrients in kombucha, there's tons of valuable info. However, there is no mention at all of the fact that you can start your own culture from scratch. Also, the advice for dealing with mold is to simply wash it off the culture! Yuck!