A fun, interactive site provided by City University Law School, with information on legal research, including: understanding legal abbreviations, speed reading, reading authorities, finding legal sources, avoiding plagiarism, and keeping up to date with law.
The Online Writing Lab (OWL) at Purdue University contains a wealth of supportive material suitable for all subjects, covering research strategies, using internet resources, avoiding plagiarism, and different citation styles (APA, MLA and Chicago Manual of Style).
The Institute of Advanced Legal Studies, University of London provides sets of legal research guides for different subjects and jurisdictions, and for international law. You can also access guides to the main legal databases.
Harvard Law School Library provides subject area research guides and video tutorials on using legal databases.
GlobaLex publishes a wide range of legal research tools on its website.