The Internet Encyclopedia of Philosophy (IEP) is a non-profit organization that provides open access to detailed, scholarly information on key topics and philosophers in all areas of philosophy. The staff of 30 editors and approximately 300 authors hold doctorate degrees and are professors at colleges and universities around the world (though mostly from English-speaking countries). Submissions are peer reviewed by specialists according to strict criteria. The site can be searched using a Google interface or easily browsed using the alphabetical hotlinks. There is also a useful Time-line of Western Philosophy.
PhilPapers is a comprehensive index and bibliography of philosophy maintained by the community of philosophers. PhilPapers is the largest open access archive in philosophy. This resource includes journals, books, open access archives, and personal pages maintained by academics.