CHEMINFO: Chemical Information Sources from Indiana University - http://www.indiana.edu/~cheminfo/ Site designed to help people find and learn how to use chemical information resources on the Internet and elsewhere. Email discussion list available.
Sci.Chem FAQ - http://www.faqs.org/faqs/sci/chem-faq/part1/ A fairly comprehensive list of frequently asked questions and answers about chemistry and related topics.
Chemical Forums - http://www.chemicalforums.com/ Discussion boards for all areas of chemistry, at levels ranging from high school to graduate school and practicing chemists. Site also includes web directory, periodic table, articles, and reference tables.
BlueObelisk - http://blueobelisk.sourceforge.net/ Project to develop resources for chemistry based around the concepts of open data, open standards and open source. Members list, details of activities, mailing list, news, and publications.
Molecule of the Day - http://scienceblogs.com/moleculeoftheday/ Weblog explains the relationship between chemistry and real life to non-chemists.