After Register Allow Users to Upload Files

I’m not sure how to find what I am looking for. I am looking for a Plug-in or a wayto allow Registered Users to upload a file. I am designing a Tee Shirt company’s page and went with WP for many reasons. I have almost all of the functionality that they need except for this.

I’d like to have an upload page that requires people to register first then allows them to upload an .eps, .jpg, .psd or whatever. I don’t just want anyone to be able to upload any type of file for obvious reasons.

Has anyone had any luck with this sort of thing? Or know where/how I can accomplish this? I know about writing a PHP uploader but was hoping to be able to implement it with WP somehow too!

Thanks guys and your help is always appreciated!