What is the ruling on selling subscriptions to file-sharing websites like RapidShare?

It is permissible to sell subscriptions to file-sharing websites to those who are known or predominantly presumed to use them for permissible purposes. It is forbidden to sell them to those who are known or predominantly presumed to use them for forbidden purposes. If the situation is unknown, the default is permissibility of sale, based on the Almighty's saying: "And Allah has permitted trade." The sin of forbidden use falls upon the buyer. Website owners should monitor content and stipulate against placing files that are forbidden by Islamic law. The advice is not to work in this field to avoid falling into doubtful matters, as the Prophet, peace and blessings be upon him, said: "Leave that which makes you doubt for that which does not make you doubt," and "Whoever guards himself against doubtful matters, he has indeed cleansed his religion and his honor."