sorry, I had a scheduled c-section with Emma, but IndysDad did have a good suggestion - I've read that it should work.
Castor oil will clean you out - but not in the way you're hoping for. and it could also make the baby have a bowl movement before he/she is born --that would be a BIG NO NO!!
I know you said " don't say have sex", but really all you need is the semen, that's what will trigger the contractions...
Nipple stimulation releases oxytocin, which can trigger contractions too, but some doctors believe it can make for longer and stronger contractions, and slow the babies heart. so they recommend that you be monitored if you go that route... beside, unless you are REALLY bored, it could take HOURS of stimulation to have an effect.
Stress will only delay everything -- baby will be here when the time is right, unfortunately, for now, you are stuck walking around with a water ballon between your legs. try to get comfy and relax the best you can. easier said than done, I know.
is this your first? oooooh, I'm so excited for you!! sending you hugs and prayers -- sandy