The American Bar Association posts lists of all ABA-approved law schools. FindLaw posts a state-by-state list of all U.S. law schools that gives you the school's address & telephone number and links to the school's Web page, library catalog and a law review Web sites. FindLaw also posts links to Foreign Law School Web sites.
Online rankings for individual law schools include the U.S. News and World Report, Above the Law's Top 50 Law Schools, Leiter's Law School Rankings and The Best 172 Law Schools by The Princeton Review and Super Lawyers.
In print, a leading law school ranking is The Gourman Report: A Rating of Graduate and Professional Programs in American and International Universities. The April issue of The American Lawyer traditionally features law school rankings based on hiring at big firms and major cities, Supreme Court clerkships and Skadden Fellowships. The LSAC Official Guide to ABA-Approved Law Schools publishes job placement figures, which can be used to rank schools.
For choosing a school, I recommend The Insider's Guide to Law Schools, which gives you a better idea of what life is like at the school than you're likely to read anywhere else.
For even more information, you can also search articles about the school (see the "News" and/or "Periodicals" entries).