Not all web sites make it easy for users to delete their accounts, and some might actually make it so difficult that it's nearly impossible to do without help. That's where AccountKiller comes into play, because it not only gives clear and simple instructions for deleting accounts at all the most popular sites, but it also uses a definitive colour-coding system to rate each one's "ease of service."
The colours used to rate sites are white, grey, and black. Sites rated as "white" make it relatively easy for an average user to delete an account there. "Grey" sites aren't exceedingly difficult, but they're not exactly stellar about facilitating the process, either. "Black" sites, as you may have guessed by now, are sites that make it so difficult to delete an account that you may not want to create one at all.
AccountKiller currently tracks and rates over 150 sites, including major destinations such as Facebook (grey), Gmail (white), iTunes (black) and Skype (black). Some of the ratings are quite surprising, and some aren't, but clicking through to a site's information page gives a detailed description of the process for deleting an account there.
While collecting a comprehensive list and providing instructions is great, the real gem here might be for blacklisted sites. When a site is blacklisted, AccountKiller includes any links or phone numbers its staff could find that might be needed or helpful to finish the job.