Document Management with CRMOD

I'm looking for a document management system that is integrated with CRMOD.  We need the ability to prepare document plans per contact (which documents are necessary), record when a document has been received with notification to the appropriate user, and track the review/approval of documents.  Documents are often used as part of a submission to an outside organization (e.g. college application), so the ability to easily retrieve a copy of a document is important.
Today, we've configured a custom object to be the "Document Library".  With a few clicks, the user is able to load a document.  But, the tracking of document plans, document receipt, and review/approval is a lot of work.  Is there an existing software solution available that keeps us from "reinventing the wheel"?