JustCite - Context's comprehensive, cross-referenced index to key UK and European legal and official information. - http://www.justcite.co.uk/
AALL Universal Citation Guide - From the American Association of Law Librarians, Edition 2.1 is part of an ongoing effort toward the goal of uniform, non-commercial legal citation. - http://www.aallnet.org/committee/citation/ucg/index.html
Shepard's Citations - Publisher of materials allowing attorneys to verify the validity of case law and statutes. - http://www.shepards.com/