Nabbed this lovely recipe from hal3000.cx.  It's surprisingly 
delicious.  Don't skimp on the ginger, extra's ok.  I do love
ginger.

                               Molasses Switchel
   While many harvest drinks relied on fruit juices, switchel
   was a spicy, vinegary drink without fruit juice. It proved
   unusually thirst-quenching, and aided in digestion after the
   heavy harvest meals. The switchel served durring the work harvest
   was nonalcoholic, meaning that the harvest hands could successfully
   negotiate the evening dance that followed the elaborate picnic, or
   "supper on the ground." Although this switchel recipe is noncarbonated
   as well as nonalcoholic, the recipe may be modified to create a
   carbonated drink, or a beer or wine type alcoholic beverage if desired.

  3 to 4 quarts water
  1/2 cup apple cider vinegar
  1 1/2 cups sugar
  1/3 cup light molasses
  2 oz fresh grated gingerroot

1. Combine 1 quart water, the vinegar, sugar, molasses, and
gingerroot and simmer for 15 minutes uncovered. Remove from
heat, cover, and allow to cool for 30 minutes.
2. Pour slowly into a glass jug containing 2 1/2 quarts water.
Top off with water to make 1 gallon.
3. * For a traditional noncarbonated switchel * : Chill immediately
Bottling and capping is optional.
4. * For a carbonated drink * : Place 1/8 teaspoon granulated ale
yeast into a teacup containing 1/4 cup lukewarm water and allow
to rehydrate a few minutes. After verifying that the temperature
in the jug is not hotter than lukewarm, add yeast water to the
jug, cap, and invert to mix contents. Bottle, then store the
bottles in a dark place. Check carbonation after 48 hours and
again after 72 hours. When carbonation is right, refrigerate.
5. * for a wine type switchel * follow the carbonated drink but
ferment instead of bottle.
6. * for a beer type switchel * ferment then cap after adding
more yeast when the desired fermentation has occured.

From the book:
Homemade
Root Beer
Soda
& Pop
by Stephen Cresswell
Tried a batch of noncarbonated switchel and loved it!
Fast and easy to make, tastes along the lines of an iced-tea
with lemon and sugar.