I definitely like the idea of giving characters quirks. To me, even heroes have flaws and strange eccentricities.
Ooh, here's some good ones I just thought of:
*Instead of a having a real job, claim to be an "adventurer" and insist that there's lots of treasure to be found in abandoned tombs and temples.
*Hang around with a group of three or four like-minded individuals, often for no good reason but to go kill things in aforementioned places.
*Purposely put your life, soul, and sanity in danger for a better magic sword.
Now that I think of it, I can see why they didn't put a quirks & flaws system into 3rd Edition . . . it's built right in!
-S