On the day that Facebook has gone public, it is also being sued for $15 billion by users who claim that Facebook was tracking their Internet usage, even after they had logged out of Facebook. The lawsuit is a combination of 21 other cases that have been filed against Facebook. This is just another case in a long string of privacy issues that Facebook has run into recently.

Germany is actually warning its business investors to stay away from Facebook’s IPO because they say that the social network actually violates European privacy laws, and that they are soon going to try and stop Facebook from transferring personal user information from Europe back to the U.S. Another European activist organization is trying to force Facebook to let their users vote on the company’s new privacy policies. And all of this comes on the heels of other social networking sites, such as Twitter, offering users a “Do Not Track” privacy option on their site.

If you are worried about your own privacy on Facebook, check out our video tutorial on how to adjust your privacy settings. You can also check out AVG’s new “Do Not Track” function on their security software suite, which will block sites like Facebook from tracking your Internet usage. If you want to make sure your identity hasn’t been stolen due to online privacy issues, check out our reviews of the top identity theft protection sites.