Suite 101 has started sending out reports every month on how much your articles earn. From these reports I've learned:
One article can earn you over 19% of your overall earnings Sometimes your best earning articles are ones with a long tail keywords Older articles (I mean years old) tend to earn me the most money An article doesn't have to get a lot of page views to make a lot of money A large amount of articles may not earn you anything one month, but that can change in a few weeks Seasonal articles can make you a lot of fast cash, even if they're brand new