The Big Bang

So, I just rewatched the Doctor Who season 5 ender, The Big Bang.  (Just as awesome as the first time I saw it.)  And now I wonder: first, how come River could remember the Doctor?  Enough to plant her (empty) diary and walk by at just the right time to prompt Amy's memories?  And second, with cracks scattered hither and yon across the universe Amy can't have been the only person who lived in close proximity to one for a long time.  I mean, yeah, most people who did probably got sucked in, like her parents did; and yeah, given that this is the Doctor, he probably was drawn to them in some fashion and saw a statistically high percentage of them.  Still.  Are there other boys and girls out there with  Amy's ability?  What do they do with them, how does it affect their lives?  I think this would be a great idea for fic, but nothing's stirring.  (And, anyway, I don't want to write anything else until I'm done with this ficlet about Worf.)