What backstories have you used in New Vegas and how well have they worked out? I'm about to need a new one.
I've always enjoyed backstories from the East: Caesar's Lands. My current character never experienced Caesar's reign, but he saw the chaos that came before it. I don't have much more than that.
My last backstory, and by far my favorite, was the lone survivor of a tribe destroyed by Caesar. I think it works exceptionally well. Tribals can have a personal reason to hate Caesar, but also an alienation from the Profligate work that can justify working with Caesar against it.