Internet Broadway Database
A take-off of the movie database that bills itself as the official source of information about Broadway; has links to official sites for each show currently running, as well as archives and news. Useful site search feature.

Live Broadway
Broadway show information, as well as news, research, tours, ticketing and awards.

Play Database
Site allows searches of over 12,000 plays and monologues by title, author, cast size, length, synopsis, and so on. No frills, but easy to use and very helpful.

Playbill
Theater/musical news primarily for New York and London, but also for regional theaters and touring shows. Includes an award database, frequently updated headlines about the theater business and actors, profiles, and show grosses.

Stage and Song
Site is geared toward actors and singers, but has useful listings of regional theaters, schools, organizations, and auditions.

Stagespecs Online
Site has useful glossary of stage terms, as well as links to detailed information about theaters across the United States, industry news, and theater links.

The New York Theatre Experience
Listings of current plays, acts, and musicals on, off, and off-off Broadway in New York City, plus reviews and archives of reviews back to 1997.

The Stage
News headlines, reviews, and a theatre index that lists openings and venues (focus is on the UK, but there is much from the rest of the world also). The theatre index includes links to multitudes of theatres' own websites.

Theatermania
Theater news, listings, and reviews for shows all over the United States. Comprehensive source of ticketing, cast, location, and schedule information, including archives.