One of my tools that works well to fire the players (and my own) imaginations requires creation of a family tree. I want mother and father and brothers and sisters and a few aunts and uncles, grand parents, then "who were your neigbors, best friend, classmates, etc." This works particularly well when starting with level one characters and is always useful when a party will be playing in and around their home town, as it provides the GM with quick and easy friends, foes, duties, responsibilities and the working in of repercussions for flaws and talents that promote PC growth and the storyline.
No one is born in a vacuum, yet to many adventuring parties develop that feel. Let them meet their mothers favorite cuzin Hester who is now in a bad way with the local theives guild/gang, and make him really unlikable but holding a letter from mommy dearest begging her brave and strong son to help her good cousin in his need against such nasty local thugs in the big city. And if your PC took some lame flaw like SENSE OF DUTY: FAMILY, so much the better.
