we use a plugin called flutter with our wordpress install, which allows us to add extra fields to a create a post page.
We have added fields for extra image & file uploads, basically we just need the content that is uploaded to appear on the post’s page in the frontend (see attached screenshot).
flutter allows you to do this quite easily, docs/manual here: http://www.scribd.com/doc/8790279/Flutter-Documentation
any questions please ask, winning bidder will be used for future work.