Another milestone falls next week for Facebook when the 500 millionth member is expected to join. To mark the occasion, the site is collecting "Facebook Stories" from users about how the site affected their lives, reports the All Things Digital blog of the Wall Street Journal. The stories (submit them here) must be told in 420 characters, same as a status update, and the favorites will be featured on a website within Facebook. ("Get ready for one million really creepy stalking stories," says Adrian Chen at Gawker.)