I'm sorry that neuronix is arguing based on personal anecdote, rather than on study, but he probably just doesn't have time/interest to go in and give you a more scientific statement. Go to pubmed, search for "osteopathic manipulation" and the results will set you free. There are studies that show that 50% of osteopathic physicians NEVER use osteopathic manipulation in their practice, and only about 15% claim to use it "often." In and of itself, this shows most osteopaths think it is bogus. If you then look at studies comparing osteopathic manipulation to placebo, you also see that the studies that have been done so far show osteopathic manipulation to have no more effect than placebo.
There is a big difference between the public's fetish for "natural" healing (hey, HIV, bubonic plague, tuberculosis are "natural," human life expectancy fifteen thousand years ago before modern science when everything was "natural" was 1/3 of what it is today, let's all go back to a more natural world because it's so wonderful) and any documented evidence that it has positive effects on healthcare outcomes.
I'm afraid OMM falls into much the same category as accupuncture and many herbal remedies, which is not to say that it's harmful or that it doesn't give people a sense of hope, but that honest people going into a field that is dominated on scientific principles shouldn't be intellectually deceiving themselves about its efficacy.