Center for Creative Leadership (CCL) (sign-up for free monthly email subscription to Leading Effectively is available on the home page)
Gallup Management Journal (has a variety of management articles spanning all types of industries, but can specifically review healthcare by choosing "Industry Focus" tab)
Good to Great by Jim Collins (suggested starting points from home page are: "It's in the Research" and "Laboratory")
Harvard Business School (HBS), Working Knowledge (sign-up for free weekly email subscription to HBS Newsletter is available on the home page)
Winning Workplaces (good resource for front-line supervisors; sign-up for free monthly email subscription to Winning Workplaces Newsletter is available on the home page)