There is a company that makes new production bits for Yankee drivers, Lee Valley (of Canada).
Hex adapter: http://www.leevalley.com/US/wood/page.aspx?p=57809&cat=1,43411,43417
Screwdriver bits: http://www.leevalley.com/US/wood/page.aspx?p=66021&cat=1,43411,43417