At your prompting I have begun a section on
http://distributedresearch.net/wiki/index.php/Action_Research,
"Beginners' Guides to Action Research"
A good place to start might be "infed", the informal education
homepage.
The page on action research is just the sort of good, general overview
you would expect from infed: http://www.infed.org/research/b-actres.htm
Two traditions are identified, the "British" version which is concerned
with enquiries into improving praxis, particularly but by no means
exclusively in the field of education, and a more radical "American"
version which is concerned with attempts to bring about social change.
Distributed Action Research in the early stages can be closely linked
with the first version, where it may be employed to find ways of
improving the facilitation of online communities, particularly
communities of practice. DAR may also be relevant to the emancipatory
version, perhaps through the international links which the new
communications network enables.
Another good overview with a self explanatory title can be found in
Rory O'Brien's paper from 1998:
"An Overview of the Methodological Approach of Action Research"
http://www.web.net/~robrien/papers/arfinal.html
Any other suggestions?