EthicShare is a complex site maintained by scholars and librarians that features resources on the study of ethics.
Internet Encyclopedia of Philosophy is an academic, open source reference source on topics related to philosophy. Entries are edited by scholars in Philosophy.
PhilPapers is a comprehensive directory of online philosophical articles and books by academic philosophers.
Stanford Encyclopedia of Philosophy is sponsored by Stanford University and provides concise and short articles on philosophy topics that are edited by experts in Philosophy.