Allow non registered readers to submit their posts.

hi,
Is there any way to add posts by the readers, who are not registered?
I want the readers to allow send their stories as their posts. When I approve them they will be displayed as posts. It will allow all the readers to add post(who are note registered in my site too). Is there any way to add this to me theme or any plugins available doing this?

Please suggest me a solution.

Thanks in advance.
Safeer ali