LeaderValues (http://www.leader-values.com) is consistently in Google's top 10 for "Leadership Development", and was founded in 1997. It is essentially a "non profit" destination, serving as a personal passion of founder Mick Yates (bio at http://www.leader-values.com/Conten…tailID=830.
It is well respected as an "honest broker" in the space, with excellent editorial control and easy access to new materials of all kinds.
The site's tag line is "getting better results, together".
First, it helps Leaders in all kinds of organizations develop their skills. Second, it provides students of Leadership with one of the best meeting places on leadership, organizational innovation and value systems on the 'net.
LeaderValues is very well positioned as one of the most popular free resource centers. The site has one of the widest collections to browse and study - searchable Themes (550+ entries), Links (500+ entries), Magazine Articles (350+), Books (400+), Quotations (700+) and more.
There is also a regular newsletter. Theme areas include leadership & value systems, innovation, complexity, culture, assessment, and organizational change.
Mick's Leadership Blog (http://www.leader-values.com/Wordpress) has just been relaunched and is a popular destination in its own right.