Theatre and Performing Arts  

An index of journals and books on the subjects of folklore, languages, linguistics, and literature. This is excellent for getting scholarly critiques of theatre, but it has no play reviews of specific performances.

This is a general database, so there will be both scholarly and popular theatre articles here. Play reviews included.

Another general database that is an excellent source for both scholarly and popular works. Because ProQuest has a tremendous number of newspapers, you can get reviews of plays that appeared in specific cities.