The Martindale-Hubbell Law Digests (near the end of the set) provide a summary of the law of each state by subject. The National Survey of State Laws provides a state-by-state analysis of each state's laws in major areas (e.g., interest rates, age of consent, grounds for divorce, civil and criminal statutes of limitations, negligence, will, taxes, etc.), which is keyed to each state's statutes; the Survey is available in print or on Westlaw (STSURVEYS). Nyberg's Subject Compilations of State Laws is an annual bibliography of law review articles and Web sites that compile the state laws (or give you sites to the relevant state laws) on a particular subject - it's just what you need when someone asks for a 50-state survey of Limited Liability Company laws.
Lynn Hellebust's State Legislative Sourcebook provides in-dept information on how to find out about each state's legislature, legislative process, legislators, legislative histories, lobbying, newspapers, Registers, etc.
Westlaw also offers 50-state surveys comparing state laws (SURVEYS) and state regulations (REG-SURVEYS).
For more specific information, see "State Statutes" and/or the entry for a particular state. For Bill Tracking, see "State Bills."
Historical Code Sections: Lexis and Westlaw have archived editions of most state codes back to the early 1990s. For copies of sections from older codes, call state or academic libraries in the relevant state ... or the library of the New York County Lawyers' Association (212-267-6646), which keeps historical volumes from the codes of all states and D.C.