at www.planetgreengame.com
and here's some information from the game:

The City of Melbourne, Australia has sent a ground-breaking goal of zero net emissions for 2020. To achieve this, the city provided energy audits and retrofit plans to the 20 largest commercial buildings resulting in annual reductions of 11,500 tons of green house gasses.
The city has also set strong targets for its use of renewable energy, with a goal of increasing use of 50% of projected demands by 2010. The city currently purchases 23% of its power from renewable sources, including wind, landfill/bio gas generation and pulp and paper biomass co-generation.

In the l990’s, the City of Berlin, Germany, implemented a broad modernization program for public and privately-owned apartments - improving insulation and promoting efficient deign and construction and installing photovoltaic cells. Over the span of 15 years, Berlin modernized about 600,000 apartments, or about one-third of the apartment buildings in the city, yielding a 50% reduction in energy use. Berlin also established an educational program to spread knowledge of energy saving technologies and practical energy efficiency measures.