AccountKiller is an interesting website that provides instructions on how to delete your account from most major online sites (e.g. Skype, Facebook, Live.com, Yahoo, Google, Twitter, etc.)
What do you do when you no longer use an online site? Most users unfortunately just stop visiting the site but never go through the process of deleting their accounts. When you ask them why, they say it is "too complicated" or that "they couldn't figure it out".
AccountKiller provide instructions for most major online sites making the delete process as easy as possible. Interestingly the site has a whitelist (sites that allow deletion of user accounts) and blacklist (sites that do not allow you to delete your account & information).
This is a great site to bookmark and use.