We'll try to aggregate some useful sets of resources, but it will take time. Hopefully this page will grow into something useful. We'll add stuff as we find it.
Sol's website has links, data/computing stuff, Matlab/Stata code and labs and books for interdisciplinary researchers
Some institutional resources hosted by the Sustainable Development Doctoral Society
The Open Energy Info wiki
A database of micro-surveys around the world
The official data site for the US government and the government's meta-list of data-holding websites.
Wolfram-alpha for randomly connected bits of information
Gapminder for visualizing large amounts of international and domestic data (now they have FAO data too)
Carleton College's site for resources on spatial data analysis (books, programs, data, etc.)
Earthscan's catalogs for academic books (some textbooks too) on issues surrounding "sustainability"
Timetric for accessing and visualizing time series data from around the world.
Michael Kremer's data set website (economics)
The EPA Data Finder for US environmental and pollution data.
Eurostat database for statistics about the European Union.
Australian Bureau of Statistics databases.
National Statistical Office of the Philippines.
United States Department of Agriculture National Agricultural Statistics Service (with database).
The IRI/LDEO Climate Data Library full of formatted climate data (with viewing tools).
United Nations' database
Intergovernmental Panel on Climate Change Data Distribution Center
University of Texas Map Library
David Rumsey Map Collection
Inter-University Consortium for Political and Social Research Data Archives
RealClimate's climate data catalogue
Zanran is Google for data
Aiddata has data on development aid
Reanalyses.org is a wiki site for reanalyzed climate data (discussed briefly here)
NCAR's Climate Data Guide (new and very nice)
NOAA's Earth System Research Laboratory Gridded Data Collection
Boundlessnow provides open access textbooks
Annual Review of Resource Economics
Spatial-analyst.net is a wiki with lots of resources on global datasets, also code for R users
A resource list at NCAR Research Applications Laboratory for climate, water and society
International Household Survey Network has a catalogue of many household surveys conducted around the world
Masayuki Kudamatsu's Dev Econ Data blog has links to a variety of development econ-relevant data sources