I remember Danah Boyd writing about the meaning of Facebook and MySpace for young soldiers. MySpace is therefore banned because young soldiers started telling their friends at home whats really going on in Iraq. And that`s all but positive advertisment for the army.

http://www.danah.org/papers/essays/ClassDivisions.html

The swiss company KAYWA gives you the opportunity to make QR-Codes for own homepage(registration necessary). They also provide a reader for mobile phones.

http://reader.kaywa.com/en