Interesting stats there. If I found a phone like that, the first thing I'd do is obviously look for the contact info of the person who owned it, and I'll admit I'd also probably be tempted to look through some photos, or music, or stuff of that nature (not saying I definitely would, but there's a fair chance of it).
But beyond that, I wouldn't be poking around with emails and definitely wouldn't consider trying to access bank information or anything private like that. That extends well beyond reasonable curiosity and is too much of an invasion of privacy.
It makes you think though, especially with how much smartphones can do these days.