I had a thread a few weeks back on this exact same issue. I had bought an Armadillo tire for the back because of multiple flats, but then continued to get more flats on the Armadillo through tiny stones. I had also been getting pinch flats due to not having the tires inflated enough. That was solved by simply figuring out what inflation I should have based upon the amount of weight of the bike and myself and inflating each tire appropriately.

So I've solved the multiple flats issue by getting rid of the Armadillo and replacing it with a Gatorskin, which I now have on both front and back, and haven't gotten any flats on them in a few hundred miles of riding.