Infomine: Scholarly Internet Resource Collections
"Intended for the introduction and use of Internet resources of relevance to faculty, students, and research staff at the university level. It is being offered as a virtual library and  reference tool containing highly useful Internet resources including databases, electronic journals, electronic books, bulletin boards, listservs, online library card catalogs, articles and directories of researchers, among many other types of information".  

Internet Public Library  

Librarians' Index to the Internet
Excellent annotated site of reputable web sites.  Categories are varied and numerous. A great  tool for finding information about web sites in any field, including libraries of all types.