According to NACO: Effective August 2, 2010 down-loadable products, except the National Flight Database (DNFD) will be available to the public free of charge on our public website
Free charts can be found at: http://aeronav.faa.gov/index.asp?xml=aeronav/applications/VFR/chartlist_sect
Other free digital products can be found at:http://aeronav.faa.gov/index.asp?xml=aeronav/applications