The Legal Scholarship Network publishes a series of electronic journals of abstracts -- of working papers as well as articles -- in various areas of law. The Legal Scholarship Network also publishes weekly Professional Announcements that include announcements such as important professional meetings, calls for papers and special issues of journals, and Professional Job Listings.
The Berkeley Electronic Press hosts working papers from many law schools, including Yale, Berkeley, Michigan, and Virginia, and is especially useful for law and economics research. The searching is unreliable, but you can browse papers by topic.