Yes, I too was rather surprised as to the lack of response to the question.
I have heard rumors of good rental yields coming out of such areas as:
Upstate New York, i.e. Buffalo/Rochester
Detroit and the rest of the rust belt.
Katrina affected parts of Lousiana
Parts of Canada close to the oil sands extraction sites
But, we all know what the internet like is for hype and spin - I was looking for some hard facts and data, or just some other possible areas worthy of further investigation.