According to the Environmental Defense Fund, heating systems cause 50% more pollution in New York City than cars and trucks. EDF obtained data from the New York City Department of Environmental Protection in early 2009 showing which buildings in the city use the "dirty" No. 4 or No. 6 heating oil, as opposed to the relatively cleaner-burning No. 2 oil or natural gas. This Flash-based map, created from that data, shows a building-by-building status of heating oil in use, as well as pending applications for fuel changes. In addition, this map features an address search widget so that you can look for a specific building directly.
Nonprofit-focused article on Google Earth Outreach and their efforts to promote the use of GE and related software in the nonprofit sector, as well as some nice screenshots from MapTogether favorite IloveMountains.org.