Michel Genzuk: A Synthesis of Ethnographic Research - a nice compact text.
See also the study-blog entry for 2011: here
Action research: Rory O'Brien: Overview of the Methodological Approach of Action Research
(Sociological) Intervention: Jacques Hamel: Sociology, Common Sense and Qualitative Methodology.
Design Probes: Tuuli Mattelmäki: Design Probes. (You can download this as pdf straight from internets.)
Design Research: Liz Sanders: An Evolving Map of Design Practices and Design Research (maybe a good overview in case you're interested.)