I get stamped every time I go back to the US. The only question I've ever been asked is if I have any food with me. (I'm always tempted to say, "Don't they feed you in this job?" but I know better than to joke with these people.)
I do know one US citizen who has been living in England for years, who is routinely questioned on re-entry to the States about what he does in London and why he chose to leave America. I dread similar questioning because I don't want to reveal that I have a gay partner who is a Brit, for fear that my gf will then be refused entry to the US on that basis. So far everything's been fine, let's hope it stays that way.
For stamping, though, I think Germany is the worst. They stamp you in
and out. Since I go there a lot, my passport is filling up quickly.

And of course, at least on the Eurostar, France and Belgium don't bother stamping you at all. Go figure.
