littleredcrimson just completed my #1 goal! YAY
You were in The Dark Knight?!? WICKED!!
How I did it: One of my friends sent me a posting calling for extras for the Dark Knight movie when it was filming in Chicago. She and I both volunteered through a nonprofit which meant our pay would go to the nonprofit. We were cast for an outdoor crowd scene. We got an email letting us know what to wear (dark clothes befitting a cool autumn day), and where and what time to show up (unbelievably early). We spent 12 hours on the set, most of it on our feet, trying to look either sad or scared.
Lessons & tips: Wear comfortable shoes
Bring something to read or do during down time
Be friendly with the people around you -- you'll be seeing them all day.
Resources: Craigslist (where the posting was found).