My picture posted on a website without my permission?
That is the danger of the internet. Any picture you post can be copied and passed off as someone elses. The only thing you can really do is to contact the administrator of the site in question and demand it be removed but, in reality, you may not have any luck in doing so. Also be careful of the sites you contact. They may ask things such as proof of identity and personal details, both of which can be used in identity theft. If the picture is non-compromising and only posted in one place, I would just let things be. If it is used maliciously and/or illegally, you should seek advice from either law enforcement or the legal profession.