In October 2010, Facebook made available a downloadable zipped archive of your "sensitive information" to any user that wishes to access it. You make a query to the server to prepare your folder and it's available for download within hours. When I finally opened it, I was shocked at what I found.
At 33MB long, it contained all my profile information - past and present - likes, dislikes, comments, posts, photos and videos. Everything I had ever typed into a white field with a blue button marked "Comment" underneath. Interestingly, one can mark the dates of occasions, when significant people entered (and departed) one's life and retrace the origin and evolution of shitty internet memes.
That's all great, but what happens when it gets into the wrong hands?
The package is so convenient, any user that can at least "use" Facebook is able to navigate through it. It's akin to IRC or MSN Messenger chatlogs in that everything written is timestamped and all the links are clickable right from within the (very very) long homepage. If some kind of savvy private investigator or kid with a keylogger nabs your password they can access your complete Facebook record. They'd also need access to your email; but to be honest what kind of stretch is that from getting one's Facebook password? As great the trip down memory lane is, the more chilling it gets as you realize who else might be looking at this information - those we have "authorized" to or not.
Of course, all of this is used to aggregate "targeted ads" with parts of it sold to private corporations. I can't exactly criticize them for their advertising function since I have used it myself. But then again, I've never been privy to the exact information it uses.
Like the tagline of the Social Network suggests, you don't make 500 million friends without making a few enemies and your company most certainly doesn't get a market valuation of $50 billion without selling something. Of course, information is as much of an asset as an abstract financial instrument (like a derivative security - it is essentially ephemeral and may become worthless over time as the market shifts); Facebook will need to figure out new ways of goading new information out of you to keep its targeted advertising relevant. Newspapers and other marketers had to "guess" where trends were heading and who their target demographic was - now the verisimilitude of information that marketers possess to attract potential buyers is phenomenally heightened by Facebook.
So what can people theoretically do with your entire "wall" page, photos and videos? Well, who knows? Assuming you posted whatever you posted for a decent enough reason, you ought to have nothing to fear. Take some comfort if you plan to run for public office; perhaps in the future a "semi-nude Facebook photo" will become the new "I smoked pot but didn't inhale."