I got this from a friend of mine:
YOGURT (HOW TO MAKE)
1 QUART MILK AT ROOM TEMPERATURE
1 HEAPING TBLSP PLAIN COMMERCIAL YOGURT AT ROOM TEMPERATURE
POUR MILK INTO POT. HEAT AND STIR OVER MEDIUM-LOW HEAT UNTIL IT BOILS. REMOVE FROM HEAT. PARTIALLY FILL YOUR KITCHEN SINK WITH COLD WATER, IMMERSE POT IN WATER TO COOL THE MILK TEMP DOWN TO A LUKE WARM 110 deg F. STIR THE MILK OCCASIONALLY, SO THAT COOLING WILL BE EVEN. TO DETERMINE 110 DEG, IMMERSE PINKY INTO MILK. TEMPERATURE SHOULD BE WARMER THAN BODY TEMP, BUT NOT HOT ENOUGH TO HAVE TO REMOVE YOUR FINGER.
WHEN THE MILK IS 110 DEG, REMOVE POT FROM THE WATER.WORKING QUICKLY, STIR THE COMMERCIAL YOGURT INTO SMALL MIXING BOWL. SLOWLY MIX IN 1 CUP OF 110 DEGREE MILK. GRADUALLY POUR AND BLEND THE BOWLS MIXTURE BACK INTO THE POT OF MILK. STIR CONTINUOUSLY AS YOU POUR. POUR THE CONTENTS OF THE POT INTO CONTAINERS TO BE USED FOR INCUBATING. WHEN SET, REFRIGERATE FOR AT LEAST 5 HOURS BEFORE SERVING.
POUR CONTENTS OF POT INTO 4 SMALL CONTAINERS. PLACE CONTAINERS INTO LARGE, HIGH SIDED PAN. PLACE THE PAN IN AN OVEN THAT HAS BEEN PREHEATED TO 100 DEGREES, THEN TURN OFF OVEN. PLACE THE PANS IN THE OVEN AND LEAVE UNDISTURBED FOR TEN HOURS, WITHOUT PEEKING.
FLAVORINGS:
AFTER SET: (ADD MEASUREMENTS PER 8 OUNCE CUP)
PRESERVES: 4 LEVEL TBLSP
FRESH FRUITS, FROZEN OR CANNED FRUITS, FRUIT SYRUPS, SUGAR, HONEY, WHEAT GERM, GRANOLA, DRIED FRUITS(2 TBSP)
BEFORE SETTING(ALL FLAVORS MUST BE AT ROOM TEMP. ADD MEASUREMENTS PER CUP)
HONEY, SUGAR, PURE MAPLE SYRUP( 2 1/2 - 3 TBSP. STIR TO DISOLVE. INCUBATE ONLY 5-6 HOURS OR UNTIL JUST SET.)
VANILLA, COFFEE( TBSP AND 2 TSP INSTANT COFFEE PLUS SWEETENER TO TASTE STIRR TO DISSOLVE INCUBATE ONLY 5-6 HOURS)
I haven't made yogurt in quite a while - but we do make cheese! It's so much better than store bought!