I have a gmail account, and i registered to many websites using that email. I want to know if there is any way to know what sites are registered with this email. (for example i can sign to facebook, daniweb, twitter using that email and also to other websites, so how can i know what are these others websites. Does google provide this function)

Since most of the web services you mentioned are ran by different Companies they would be reluctant to share user information with each other for privacy reasons.

No they will not provide these information its against their terms and policies or their regulations, so you can't find those informations you looking for.

Thank you for replying. So the conclusion is: no solution for this mission.

you are trying to wathch anther gmail users account ?else your gmail account ?
if you register on site then they will send you mail about verification or welcome based on this you can check mail based on that criteria after all.

yes true. but what if you deleted the email. how will you know?

PixelatedKarma and kaka_bin are on right. no solution

you can check this on Google search with providing you Gmail User name in Quote. e.g: "abc@gmail.com"
this shows all the account releated with this email address.