Sites such as RapidShare, Megaupload, and Hotfile let anonymous users upload large files such as cracked software for free.

Hyperlinks to the software can then be distributed by pirates via Web sites, instant messages, or social media sites such as Twitter, said Vic DeMarines, CEO of anti-piracy software vendor V.I. Labs.

"It's incredibly easy to use. And what you get is essentially your own private FTP server," DeMarines said.

While sites such as RapidShare allow free downloads, they make their money by charging heavy downloaders for premium memberships. These memberships, such as the 30-day premium access for $6.99 Euros at Rapidshare, let users download files immediately and without any caps on bandwidth.

Trade in , whether it is movies, music or e-books or software, is what drives the popularity and business model of firms like RapidShare. The site told The New York Times earlier this year that it .