Here's a list of some useful books dealing with capital markets that have a progressive slant. I'll give them a short summary for now, and try and some post up longer reviews as I get going.
Working Capital: The power of labor's pensions
No, it's not a typo, the US-style spelling is because this book is all about workers' capital in the US. A good overview of some of the theory and practice in North America, although a little dated now. You can buy it via US Amazon.
The New Capitalists
A recently published book that tries to grapple with the implications of widespread shareownership. Probably the best overview of the whole system that has a progressive agenda and practical proposals. Even has a bit of coverage of the role of unions.
The New Global Investors
A slightly more mainstream take on shareholder engagement from corporate goverance veteran Bob Monks.
Socially responsible investment: a global revolution
This book charts the growth in the SRI movement, from the early disinvestment campaigns through to the Pensions Act disclosure amendment and so on. Written by an SRI practitioner from the Methodist Church.
A more recent take on the SRI movement in the UK. This gets into more detail and includes chapters from a range of different interested parties. Also contains quite a bit of discussion of financial analysis.