User submit plugin ??

I have a blog with funny stories and jokes – and would like users to be able to post new stuff here – but i dont want them to access all the options in the dash board ..

It should just be a screen where they can write their story ( like a comment i guess) but with a predetermined catagory –

So when they submit theier post will be published under their name and a catagory i have decided ( Jokes or Stories ) ect …

I thought maby i could modify the admin/post.php and include it on a page on the blog – but it got to complex ..

Any one know of a good solution …

Regards

Meier