plugin to let users add content but not going into the dasboard

i am looking for an plugin that lets users add content to my website but with out going to the wordpress back end eg dash board. i am setting up an website where i want users to be able to post content to my blog categories and also add images and movies from places like youtube or url links to images. but i still want the user to join. so to speak but they dont need to go to the dashboard to make an post can do it with in a form on the website its self it should also be the default user group. so maybe when they try to add content is says please login before they see the form its self ? then once loged it lets then post with there username ?. but the content the users add should go in the WordPress mod system before it goes live to the site i hope i am making my self clear any help would be great

cheers