General information about education in the U.S.
The Department of Education (the equivalent of a ministry in Europe) not only provides information about its activities. (<http://www.ed.gov/index.jhtml>) but also provides an online Teachers' Guide to information, classroom projects, classroom material and other teaching topics (<http://www.ed.gov/pubs/TeachersGuide>).
The site of Education Week and Teacher Magazine provides general news about education addressed to American teachers. Good for keeping up to date on current controversies and trends. <http://www.edweek.org>
The Education Commission of the States publishes reports on national educational issues such as national educational standards (a relatively new concept in the U.S. where education has always been locally controlled) and national examinations, as well as on education policy in the 50 states. <http://www.ecs.org/>
ERIC (the Educational Resources Information Center is an official government site which corresponds to a very large database of documents and articles on a vast range of topics concerning education. The site moved in Sept. 2004 to <http://www.eric.ed.gov/>, or you may use the private site <http://searcheric.org/> to search the abstracts and Digests produced by the ERICSM system (but documents must then be ordered).
the NCES (National Center for Education Statistics) provides an enormous amount of statistical data on education: teachers, students, schools and universities, finances and resources, diplomas, affirmative action and integration, courses of study, etc. <http://nces.ed.gov>

Charter Schools
Charter School Research is a source of information on charter schools, both those already created and new ones, as well as state policies on charter schools. It is sponsored by the Center on Reinventing Public Education: <http://www.crpe.org/cs/crpe/view/projects/1>

Liberal and New Christian Right lobbyists
The Christian Coalition is a Fundamentalist Christian group which tries to influence choice and content of textbooks, school choice, charter schools, sex-education courses, science courses (specifically evolution vs. creationism which, strange as it may seem, has a vocal if not large following in the U.S.), and religious rights and practices in an educational context (in spite of the constitutional separation of Church and State). <http://www.cc.org>
The Education Excellence Network is a conservative group which supports the campaign for national standards and opposes the teaching of multiculturalism. After 15 years of operation, it was absorbed in 1996 by the Thomas B. Fordham Foundation, which pursues similar goals. <http://www.edexcellence.net/foundation/global/index.cfm>
The website of Educational Research Analysts (http://www.textbookreviews.org/) is essentially the site of a couple, Mr. & Mrs. Mel Gabler, who have dedicated their lives to analyzing textbooks under consideration by the state of Texas for its schools, from the perspective of the Christian Right. This type of intrusion of religion into the educational sphere being unfamiliar to most Europeans, those interested in the politics of education in the US should be most interested by this website. Particularly illuminating are the pages "Meet the Gablers" and "God-given victories," the latter not only for what it says but particularly for what it avoids saying.
People for the American Way is a liberal organization that opposes the religious right and attempts to head off its efforts to censor textbooks and school library books. <http://www.pfaw.org/pfaw/general/>

School Desegregation
The Brown vs Board of Education 50th Anniversary Digital Archive is a site run by journalism students at The College of New Jersey. It is a living site in that it is constantly expanding and invites visitors to contribute material. It offers multi-media documents (video and sound) as well as links to other websites dedicated to Brown. <http://kpearson.project.tcnj.edu/>

N.B. since there is no such thing as a national university run by the Department of Education — although each state has one or more state universities — there is no central site for American universities. Each university has its own website, which you can locate by using Google.com. Each state has a State Department (or Board) of Education and a Board of Higher Education. California and New York have a Board of Regents.