Breaking my own rules
One of my personal guidelines with computers and IT is that if I accidentally receive credentials or access possibilities to other people's accounts I do not take advantage of it without consent of the owner.
Usually I get access to such information because I'm fixing computer and software problems for friends, relatives and acquaintances. But from time to time I receive account information which I didn't subscribe or enter. In the past few years it started slowly but became more over time and shown a very specific pattern: it all involves one of my mail-accounts and it seems that there is somebody out there who has a very similar mail account with only a single letter difference. And this person seems to regularly create accounts and get its own mail-address wrong. Several attempts to notify this person or get into contact were unsuccessful. At one point I even got my hands on a phone number but I never reached anyone with it.
There are still too many services and websites out there which do not require a confirmation click via email but just create an account without checking if provided mail-addresses are correct. I wouldn't mind a single mail which I don't respond to and be through with it but life isn't that easy.
I'm now pretty much fed up with the constant notifications, reminders ("...please come back to XYZ...") and mails involving such erronous subscriptions to services and websites. Especially Facebook seems to be pretty stubborn and manages to escape my filters constantly but also a pile of gaming-accounts and logins to some other websites have accumulated.
In a short while I'm going to shut down all the accounts using my mail-address. For that I'm going to request a password-reset, log in to those accounts and deactivate them (if possible). I'll try to keep information sniffing at a minimum but if I see additional possible contact info maybe I'll do another contact try. Nevertheless all accounts which show no further activity (e.g. another credential reset by the "other" user) for some time then will be shut down permanently.
Gah, I hate to do this but you left me no choice...
Update 2014-03-01: Deleting a Facebook account is nothing short of complicated. All that Facebook offers (more or less) directly available is the possibility to deactivate your account. But this is in reality just snake oil as your account still exists and allows further logins and data profiling and just hides almost everything from others. To really and permanently delete your account one has to dig deep, and I mean really really deep, in Facebooks help and info pages to almost accidentially trip over this link:
https://ssl.facebook.com/help/contact.php?show_form=delete_account
With this link you can tell Facebook to really delete your account and all associated data which they at least promise to do after a 14 day cooldown period where you can still decide to change your mind. Which I won't do as I didn't even sign up myself in the first place...