There are tons! Lets see....you can google any of these to get more info. You should be drinking red raspberry leaf tea about 3x a day, that will help tone the uterus. Walking is great, nipple stimulation, sex, the old castor oil method which I tried out of desperation and it only gave me diarreah. Black and blue cohosh tinctures, acupuncture is supposed to work well, spicy food. For me, it was get labor going or be induced at the hospital, which I did not want. The thing that finally put me over the line and into labor was, gulp, an enema. It was not pleasant, but when I got to the hospital I was 4 centimeters and did not have to have the invasive induction I was fearing. Also, you can have your doctor or midwife "strip your membranes" they basically swipe their finger between the wall of the uterus and the sac and labor generally starts within 24 hours. Oh, and some say to eat eggplant parmesean, didn't work for me but it's yummy :)
Good luck to you!