Board Source has several webinars, beside many FREE resources for Trustees.  Some webinars are fee-based but may be worth a look.  Here’s one on Board education:

Certificate of Nonprofit Board Education

Wednesdays, Feb. 4 – March 11, 2015 | 2:00 – 3:00 pm ET
This six-part webinar series covers the fundamental nonprofit governance concepts every nonprofit leader should understand, including board structure and practices, roles and responsibilities of board members, and financial and legal oversight. Designed for those who are new to board service or working with a board.