Berkley Electronic Press (Bepress) Publishes a variety of academic journals in such subjects as economics, current affairs, humanities, health and science. Also hosts institutional repositories. Search by general category or keyword.
http://www.bepress.com/ - [ Report Dead Link ]
EBSCO Online An electronic journals service available to both academic and corporate subscribers. It aggregates access to electronic journals from various publishers.
http://ejournals.ebsco.com/ - [ Report Dead Link ]
Periodicals Index Online Provides over 9 million article records, covering journals and periodicals from 1770 to 1990 in the arts, social sciences and humanities. Published online by Chadwyck-Healey. Subscription required but a free trial is available.
http://pio.chadwyck.com/ - [ Report Dead Link ]
Project Muse Subscription based academic journals site with 250 quality titles from over 40 publishers. Articles can be searched by keyword or phrase, including Boolean qualifiers. Free samples.
http://muse.jhu.edu/journals/ - [ Report Dead Link ]