Yep

With Yep 2, you can easily track over 100,000 documents like PDFs, iWork and Office documents, use Quick Look or Yeps built-in magnifier to view documents, file documents automatically into a date-based folder system within your Documents folder, create text files from dragged-in text without any naming or filing on your part, create PDFs by simply scanning documents. Add tags to classify and manage documents (Yep uses the OpenMeta tagging standard). Unlike some other applications, Yep does not store any data in a database, or move your files into any special folder or package. Edit, save and manage documents anywhere on your system.