There is a wealth of statistical material available online, much of it produced by state and federal agencies of various kinds.
An excellent resource is the Digital Social Science Center, found on the Columbia University Libraries website. Their list of data includes the following topics:
Each section includes extensive listings of citations and links for major resources in the Columbia University Libraries and accessible on the Web.
An additional collection of Statistical Resources databases can be accessed through the Columbia University Libraries' Databases page by searching by type of resource (selecting "Statistical Resources" from the dropdown menu).
For education statistics, particularly ones specific to education in the United States, the website of the National Center for Education Statistics (NCES), produced by the U.S. Department of Education's Institute of Education Statistics (IES), is a key source of information. The NCES produces several annual reports that are considered essential education resources, including the Digest of Education Statistics, the Condition of Education, and Projections of Education Statistics. The NCES site also provides access to Surveys and Programs, Data Tools, Tables and Figures, Fast Facts, a School, College, and Library Search, and other resources and search capabilities.
For international education statistics, key resources include Education at a Glance from the Organisation for Economic Co-operation and Development (OECD) and World Data on Education from the International Bureau of Education of the United Nations Education, Social and Cultural Organization (UNESCO).