Related Links
This is not intended as an overview of a large, and growing, literature, but just my, particular, view. In this area perhaps the best place to start is with my co-authors.
Deepa Narayan has done interesting work all over the globe on participation, social capital, and most recently the project on "Voices of the Poor"
Michael Woolcock has written extensively on social capital (and his forthcoming book on social capital and development will be the state of the art).
Jon Isham is doing very interesting work on "co-production" and its relation to social capital and proejct design.
The World Bank Social Capital web site is also a good source.
The Local Level Institutions Study produced research in several countries on social capital issues, including a number of papers by Christian Grootaert.
Alberto Alesina does interesting work on fractionalization (with Eliana Ferrara, who does interesting work of her own). Edward Glaeser examines mostly the private dimensions of social capital, that is how households own social connections affect outcomes.
Also, there is a web site at University of Rome on social capital that looks like it has an impressive collection of references.