SEC Edgar advanced search

http://searchwww.sec.gov/EDGARFSClient/jsp/EDGAR_MainAccess.jsp?search_text=*&sort=ReverseDate&formType=FormD&isAdv=true&stemming=true&numResults=100&fromDate=02/01/2010&toDate=07/14/2010&numResults=100

You can get only 100 per page (or is it 1000)
It displays a maximum of 8000 per search
Data available only for 4 years back

ftp://ftp.sec.gov/edgar/README.txt

Using .gz seems to be the best archive.