The web has treasures for knowledge seekers; one can even find knowledge that others pay substantial training fees for. I hope the following web sites will be of value!

Wikipedia: Introduction to Organization Development

This wiki is a well written article, a good overview, a great starting point to learn.

Read the article:  Wikipedia about OD

Organization Development Info Hubs

These two organizations provide comprehensive info on OD, with case studies, various publications and active mailing lists about events and learning opportunities.

Attend webinars and subscribe their mailing lists to connect to the happenings in the OD field:
OD Institute and
OD Network

Free online training-learning material

I like learning by browsing the internet about topics that I am interested in (e.g. EQ, influencing skills, etc.) and integrating the various blogs and articles in a format that makes the most sense to me. I highly recommend this process. And when time is limited, I recommend just visiting these sites:
Mind Tools - content for Management and Leadership training and
The LearningArchitect Life Skills Library

Quality online courses for free

The recent development in e-learning technology and network infrastructure brought a new era when knowledge really becomes available to anyone who is willing to learn.

Listen to high quality lectures or enroll a full course on Strategy or Emotional Intelligence on these excellent web sites:
Coursera and
Floating University