Well, having a profile at all means that you are subject to Facebook's terms of service, which is not only subject to change at any time, but currently grants them the right to the information that you do post - at mininum, that comprises a map of your associations, which could easily find itself in the hands of government or law enforcement agencies should they have use for it, since you signed away the rights to this information when you signed up. By your own admission, you post about the books that you read, which happens to be a very useful resource for establishing your psychological profile and your political leanings. Facebook also has rights to the images that you post, and your posts to the site not only establish your frequency of use (another behavioural indicator), but can establish patterns of behaviour - for example, times that you are most likely to be at your computer or away from home. The Facebook terms of service provide for indefinite preservation of anything you have posted to the site since you signed up, so even the things that you choose to delete from your profile indicate the extent of your privacy savvy, or the subjects, photos, etc. which you may find embarrassing or otherwise inappropriate for public consumption. Games and quizzes only make it easier for Facebook to share your data with third parties - they have no bearing on Facebook itself, and even the limited information presented above constitutes a valuable package. You may wish to consider whether handing over, without compensation of any kind, that sort of information to a company whos CEO famously declared that privacy is an "outdated concept", is a particularly wise decision.