The word "Vinegar" means "Sour wine."  Thus, the most logical thing to make vinegar out of is, you guessed it, wine.  Making your own wine vinegar is easy, and it also means that you can have more than one type.  White or red wine can be used, and you can use whatever wine you'd like (as long as it's not a sparkling wine).

You will need:
1 bottle of wine, white or red
1 tablespoon of pot barley
a non-metal container with a decent lid that will hold 1 bottle of wine

Pour the wine into the container and add the pot barley.  Cover and let stand in a warm place for a few days.  When it tastes right to you, strain and bottle.  Keep some of the liquid in the crock as a mother.  Feed it occasionally with splashes of wine, and you can use it to make a new batch in the future.  Always use the same type of wine that the mother was created with.

Note:  If you're going to keep making vinegar, don't wash the crock with soap or detergent between batches. A rinse and wipe with a lint-free paper towel is enough.