Top picks for great overall board information

Free Complete Toolkit for Boards

BoardSource's Q&A section

Subscribe to BoardCafe for a monthly e-newsletter short enough to read over a cup of coffee.

Nonprofit Genie's FAQ's on Board Development

Internet Nonprofit Center's FAQ's on Board of Directors

Info Central: Governance -- Minnesota Council of Nonprofits -- FAQ's and Templates

24-page Guide for new Board Members - Grant Thornton. 
Particularly good for board members from for-profit sector.  Includes 3 pages differentiating Not-for Profit from For-Profit Boards.

"Learn before You Lead" -- Management Assistance Program for Nonprofits, St. Paul