user generated content – how to create a post through a form on the site

I was thinking of creating some galery site, similar to http://www.css-remix.com with wordpress. WordPress is obviously not a bad system for that, every entry is a post, no problem.

Just one question: is there a way to let users submit the entry via a form and once the form is submitted, it is stored as a new unpublished post (which the admin, can check and put live)? Is there a plugin to do such a thing?

thanks for help!