This was going to be a response to Citizen Ben's comment on my Character Creation - True Background vs. Limited Future Choices post, but it got pretty long and I decided to just promote it to it's own post. Ben's comment and my response below the jump.
I've tried using supplementary character questionnaire surveys with D&D in the past too, to mixed effect, as I've had players later contradict it (one put on the questionnaire that his character abhorred casual cruelty, but was willing to toss away his animal companion in order to outrun an unspeakable horror) or just ignore it. I sent out some character questionnaires for the D&D game I'm currently running and basically had them ignored.
The more I think about it, the more I think it's not just having the character creation emphasize a real background, but having some game mechanics that reinforce the character identity. For Reign it's having the chance to have Passions, a Duty, Mission or Craving that earns you extra dice or a Problem that earns you extra XP. For Dread it's reinforced because your background is all you have (ie, no traditional character sheet).
Other games that I enjoy have some kind of identity mechanic, Fading Suns has the opposed Spirit Characteristics of "Extrovert/Introvert", "Passion/Calm" and "Faith/Ego" that help a player define and stick to a character identity. The spirit characteristics also tend to go with some of your character choices, you've probably got a higher Faith if you're a priest and a higher ego if you're a member of a tech guild, but it also provides a quick reminder to glance down at mid-game and go, wait, I'm playing an Introverted, Calm, Faithfully priest, why is my character getting so worked up and argumentative about this, does it fit?
Unknown Armies not only has a great "Obsession" that drives your PC (though that's hard to port to a game that isn't all about obsessive Magick users bending reality through their manias) but also has Passions, Fear, Rage and Noble, each of which you give a stimulus that triggers them, so if your Rage stimulus is bullies who pick on people smaller than them, there's a mechanical advantage if you fight that bully or a disadvantage if you try and ignore it. I might be tempted to borrow these passions for non-UA games to provide players a chance to define what makes their character most afraid, what drives them to anger and what brings out the best in them. Unknown Armies also a great set of Madness meters, keeping track of how hardened or freaked out a character is of Violence, the Unnatural, Helplessness, Isolation and questioning their Self. I would definately be tempted to port the madness meters to any game where I was running a horror/Lovecraftian/insanity game that didn't have a good madness mechanic of it's own. Like say, running a Ravenloft game but adding the UA passions and Madness meters on..