Wow, the Russians must really like ferment.
One of the more vile products I've ever tasted is kvass (spelled in cyrillic, if I remember correctly, KBAC).
It's sort of a non-alchoholic, sweet, yeasty barley pop.
Imagine strong beer-flavored soda pop, and you're most of the way there. But at least the flavor of beer in your mouth goes away pretty quickly, this stuff sticks with you for a while.