No doubt FOTOLIA is among the big ones. What surprised me is that it's even better (in terms of sales) than IStockPhoto and Shutterstock.
I don't know why but I would advice it's because it is localised in many countries and it sells worldwide
Follow the link for your preferred language / currency to visit Fotolia:
Fotolia UK (English / Pounds)
Fotolia USA (English / Dollars)
Fotolia Deutschland (Deutsch / Euro)
Fotolia France (Français / Euro)
Fotolia Italia (Italiano / Euro)
Fotolia Espana (Espanol / Euro)
Fotolia Portugal (Portugues / Euro)
Fotolia Brazil (Portugues / Real)
So choose your language above and
sign up to
start selling photos and earning (even if you are an amateur photographer) or to
buy low cost legal royalty free pictures (if you are a designer). Please note you only need to sign up to one site and your photos will sell worldwide thanks to automatic translations. Choose the language you are more proficient.