I have just completed a major rebuild of the programs I use to extract the filings from the SEC website and process them before they are added to the filing collection.  This rebuild has given me the flexibility to add more metadata to improve your searches.   I plan on adding SIC codes and FISCAL YEAR END.  This will improve your filtering speed if you want to include or exclude filers from your search results based on one of these characteristics.  I would appreciate suggestions about other characteristics you would like to see added to the filings to allow you to more efficiently specify a population of search results.