I was part of a book a while back called "fermentation kitchen" (I was the technical editor). It's a pretty decent overview of fermented food and drink, and I've found it very helpful in some of the things I don't do often. Pickles and kombucha are a great place to start, but don't overlook pickled carrots (just like cucumber pickles really) and other fermented foods. Probably my favorite is sauerkraut or kim chee, and both are very easy to start and pretty economical also.