MegaUpload.com with 150 million registered users with $42 million revenue has been shut down. Megaupload was a very popular file sharing site. Mega Upload domain has been seized by FBI against sharing of illegal files and for distributing pirated softwares.
Pligg is very popular CMS for creation of social bookmarking websites. Here we do have a list of social bookmarking website which are based on Pligg CMS. Grab this huge list of social bookmarking websites with IP address.