In ATR-KIM ENG FINANCIAL CORPORATION  v. ARANETA, (Del. Ch., December 21, 2006), 2006 WL 3783520, read opinion here, the Delaware Chancery Court found directors liable for acting as mere "tools" of the majority shareholder, (see footnote 129),  instead of also fulfilling their duty to protect the interests of the minority shareholders.

 The directors apparently stood idly by while the majority shareholder "looted" the company.  There is much more to commend this opinion than I have time to explore at this time, but I refer you to the post about the case on The Harvard Law School Corporate Governance Blog at the following link: The Harvard Law School Corporate Governance Blog — Directors Ignore Majority-Shareholder Malfeasance at their Peril

UPDATE: Here is an analysis by Prof. Gordon Smith, and Prof. Chiappinelli has more commentary here. 

UPDATE II: See generally,  the later decision in Sample v. Morgan (Del. Ch., Jan. 2007), here, that excoriated directors for being "unwitting and uninformed accomplices" to an entrenchment plan by other directors.