My SIL works park time at my chiro, and gets regular complimentary (and I suppose complementary ) treatments.

He diagnosed that she was having issues with her appendix - she'd had no idea, but on his recommendation went to hospital to get it looked at. It was a whisker away from rupturing, and she got it removed in under 24 hours.

He's rather awesome - though I've been to a few really crap chiros, too.

That being said, I've been to some awesome GPs, and some I wouldn't buy icecream from.