Take a look at Lippincott's Datapoints blog post I Dream of Gini for an overview of the available resources.

Download the World Income Inequality Database from the UN's University World Institute for Development Economics Research (UNU-WIDER) which is considered the largest database of GINI coefficients.

Go to Sage Data.

• Click Browse by Subject to expand.
• Next, drill down through International - World Bank - World Development Indicators, and select Poverty.
• Select one or more countries, then select Gini Index from the list of indicators.

Take a look at World Development Indicators from the World Bank for the GINI Index for selected countries and years.

Go to Gini Index - Human Development Report.

For historical, also see Measuring Income Inequality (Deininger and Squire) Database 1890-1996 from The World Bank.