Hi,
Take a look to
Fotolia a popular site for buyers and sellers of stock photograph.
...their earnings increase the more you sell with levels being 100, 1000, 5000 etc. You can also increase your earnings if you exclusively upload to them as instead of 33%(ish) it goes up to 50% (ish) depending on your level, once you reach 100 sales you can double the price of your exclusive images. In the Europe 1 credit = € 1.00 and you can take payout (Paypal or Moneybookers) anytime you are over 50 credits.
Good Luck
