I just finished reading The Spirit Level -- why equality is better for everyone -- by Richard Wilkinson and Kate Pickett. To sum it up in a few sentences, it is a very informative and enjoyable read about how inequality is a very significant factor in areas such as: community breakdown, poor health, low educational achievement, teenage pregnancy, violence. Even the Economist -- not known for its left-leaning views -- says "The evidence is hard to dispute". The thread running through the book is that a more equal society would be better for everyone. Definitely worth a read.
The Equality Trust has been launched following on from the book.