Document Management Systems

SomeGuyTyping writes: As I read about various Document Management Systems (DMS), I find they all want you to scan everything. I'm looking for a system that would allow you to tag paper and store a record of it existence and location as well as keeping track of electronic documents. Also, if any DMS has a feature to alert you of documents that are not filed yet, whether they exist or not (i.e., a permit needed for a project), that would be a major plus. Open Source is preferred, but a commercial system is not out of the question.