In order to make Denkzettel work, we need to collect the following information:
* Your Facebook and Twitter username, user id and profile picture
* Your facebook and twitter friend list (only the friends using denkzettel as well)
* the website you visit (not stored, only transmitted to the server for lookup)
* of course all content you wrote with Denkzettel
* information about Denkzettels you like
The data is only stored as long as its needed. The data is only used to provide the service itself, its not used for ads or anything.