Mavens
Brook Lyndhurst, an independent research and strategy consultancy, based in London, UK, works on projects that are concerned with understanding, promoting and delivering sustainable development.

A couple of their research reports are highly recommended reading:

The diffusion of environmental behaviours: The role of influential individuals in social networks
An investigation into the notion of ‘green’ mavens, with a view to identifying specific opportunities for communications and policy.
> Summary report
> Technical report

Public understanding of sustainable energy consumption in the home
Brook Lyndhurst was commissioned by Defra [the UK Department for Environment, Food and Rural Affairs] to conduct qualitative research into public understanding of sustainable energy consumption in the home. Through the course of 12 focus groups, in-home energy audits and follow-up, in-depth interviews, we were able to identify how energy attitudes changed across different segments of the UK population, e.g. ‘dark green’ consumers, wastage focused etc. This innovative segmentation analysis enabled us to make policy recommendations to Defra across five key behaviour goals, notably installing domestic micro-generation, insulation products and energy efficient appliances.