--Nipple Stimulation -Don't bother. It's uncomfortable. You have to stimulate your nipples for two hours a day, and even then, every woman has a threshold for oxytocin, and for some it's surprisingly high. I mean, women breastfeed through pregnancies.
--Sex/Orgasm -Do it if you want to, but it's not going to put you into labor. Semen can help ripen the cervix, but ime, it does not trigger labor. And you can have orgasms round the clock. Only thing it'll do is cause some contractions for awhile. That peter out.
--Spicy Foods -This is a complete and utter wives' tale. It won't work. If you try it, be ready to bust out the antacids after.
--Bumpy Car Rides -LOL! Seriously? Do people really think that works? Think about it. All the bumping your baby gets when you sit down, get up, walk up stairs, have sex, whatever. If that were enough to put someone into labor no one would every carry to term. This just sounds uncomfortable and miserable for someone who's 9 months pregnant.
--Acupressure -I'm doubtful. But it can't hurt.
--Acupuncture - Again, doubtful. Plus it's rather expensive.
--Red Raspberry Leaf -Will not put you into labor. Can help tone the uterus and make your labor better though. Also contains lots of good stuff to support the pregnancy.
--Castor Oil (a last resort, in my mind) -This one actually can work IF you're post dates. Do not use without supervision.
You forgot Evening Primrose Oil and Papaya Juice. EPO can help ripen the cervix, but it will not put you into labor. Papaya juice just tastes good, don't bother.
Bottom line? You cannot induce labor unless your body was ready to go anyway. Plus, there is often a reason you don't realize for your body not putting you into labor. Like, for me? I was induced with #2. And I had an OP baby with a ton of tearing. If I'd waited for her to get into the right position, I might have saved myself a whole lot of recovery pain.