History Departments Around the World, hosted by the Center for History and New Media at George Mason University, is an excellent online database which includes the addresses (URLs) and links for more than 900 history departments' web pages.
H-Net: Humanities On-line is a vast collection of discussion networks, book reviews, and other useful resources on an ever-increasing variety of fields in the humanities and social sciences. Each discussion network maintains its own website which may include: logs of the discussions, book reviews, syllabi, course outlines, class handouts, bibliographies, listings of new sources, guides to online resources, and reports on new software, data sets, cd-roms and World Wide Web sites.
Other interesting history-specific sites include the American Historical Association website, with online versions of Perspectives and information about the annual meeting, the detailed and comprehensive list of links at the History Virtual Library at the University of Kansas, the History Channel interactive website, and the History Guide which offers online lectures in ancient and European history.