About a year ago I started a half gallon batch of malt/beer vinegar (my first batch of any type of vinegar). I pitched a baby mother (acetobacter culture) harvested from a bottle of sherry vinegar, but after six months the "vinegar" just tasted like stale beer. Luckily in late September my bug-man (Matt) handed me a small culture of the bacteria he uses to make vinegar. I pitched it into the growler, and just four months later the vinegar has a sharply acetic flavor. I strained the liquid through cheesecloth into an old 750 ml bottle for storage. Time to fry some fish and chips now that I've got the homemade vinegar to spritz on it (Planning on some coleslaw as well, any other ideas?).
The same night, I happened to be racking my first batch of wine (a German white), and had an extra half gallon that couldn't fit into the secondary. I decided the best use of it would be to pour that extra wine into the last cup of dregs from the malt vinegar (and replace the rubber band and cheesecloth). With the acetobacter culture already established it shouldn't take more than a few months for it to convert the ethanol in the wine into acetic acid. I added the wine before sulfite/sorbate "stabilizing" additions, so there won't be any chemicals to disrupt the microbes. In a couple months this vinegar should be ready for vinaigrettes and marinades.
Once the white wine vinegar is ready to bottle either my sour cider or (watered down) sake will be the next meal for the bugs (after that I might even make vinegar from mead if I ever get around to making another batch). Not really sure what I'm going to do with all of that vinegar, but I'm looking forward to figuring it out.