Statistical and dataset collections provide not only the raw numbers that you can use, but they may often provide you with the methodologies and applications of this information. Organisational websites for a discipline area will also often hold statistical information, or link to good resources,
Australian Bureau of Statistics (ABS) - is Australia's National Statistical Agency. It contains current and historical data on Australia's economic & social conditions.
Increasingly, researchers around the world are making the datasets from their research available. These datasets are either described in a Dataset database, or made available from these databases.
data.gov.au - Australian Government datasets
Research Data (ANDS) - data for research from over 100 Australian research organisations, goverment agencies and cultural institutions
data.gov - US Government's Open data collectin
UNdata - data from the United Nations
Worldbank Data Catalog - included Geospatial, Microdata and Time Series
Global Biodiversity Information Facility - data about all types of life on Earth