When I was a kid I had a recipie for ginger beer which involved feeding a 'plant' for a couple of weeks. It was just a small jar with ginger sugar water and yeast and every day you needed to put a teaspoon of sugar and ginger into it. It would happily bubble away due to the yeast.
Once the plant was sufficiently strong, you mixed with a big pan of lemon and sugar water, and then bottled.
From what I remember it was quite explosive, and opening a bottle was always a ten minute job.
I'll never forget the taste though. it was great. I remember trying a different recipe and being very disappointed, I went back to the plant method!

Nick