Any plugins that allow someone to add a post to your blog but require it to be approved in the same manner a comment is approved?
You can use TDO Mini Forms Wordpress Plugin to add a page with a form for your Guest writer. Using this form a Guest writer can submit a post for review. All the Post will be listed in your administrator Dashboard. And the post will be published after approving by administrator.
You could still have the user be a "Contributer" which allows the administrator to approve the article / post before it is viewed publicly.