If you live in California, drop everything and do this

Political bit. You were warned.

Ever wanted to know what monolithic marketing agencies actually have on you in their files?

The Right to Know Act requires companies to give users access to the personal data the company has stored on them-as well as a list of all the other companies with whom that original company has shared the users' personal data-when a user requests it. It would cover California residents and would apply to both offline and online companies.
I dunno about you, but I think this is LONG overdue and should be a nationwide thing.

To support it, go here. Sorry, but this is for California residents only.

/Political bit.