Here are the House Rules we are using in my Sundered Empires game.
http://micahblackburn.wordpress.com/2012/08/31/house-rules-sundered-empires-part-1/
A few years ago, my B/X campaign began with a set of house rules written in almost the same format, and about the same length. Three years later, ACKS was born.
The wheel in the sky keeps on turning...
Wow…that’s so cool. 
“Players who write a backstory that is at least a paragraph long. get 100 experience. More involved and detailed back stories will be awarded more starting experience.”
What a great idea!
One of my players (my artist friend from the Session reports) wrote and drew an 8 page comic of his character’s back story.
…
…
o_0
Needless to say, he got more than a 100! I ended up giving him 1250.
I also find that players who are nearly at enough xp to level, suddenly feel the urge to send me a back story… 
Better late than never! I’ll tell my players about that offer today, and see how it works out for my group.
Cool! Please let me know how it works out. 
Yes +1. 'm doing this since äh time immmorial. Guess how many great backstories you’ll get. All of my players deliver at least 1 DIN A4 page of background/history (10 point font size). I give 100 XP per page but limit this to 500 XP… Works great!
Speaking of house rules slowly becoming their own game:
http://penny-arcade.com/2012/09/05/card-w4rriorz
not sure if any of you are familiar with Gabe of Penny Arcade, but he does some pretty amazing things while dungeon mastering. So know that you are in good company forging house rules!