Improv Encyclopedia - Collection of improv games, drama exercises, improv handles, and references, indexed in 27 categories. Resources can be downloaded as a pdf booklet.
The Improv Page - Bernie Roehl presents a clearinghouse for information about improvisational theatre.
International Playback Theatre Network (IPTN) - Supports development of playback theatre worldwide through its programs and services, membership benefits, training resources, administration, and contacts.
The New Improv Page - Information portal for improv. Groups, news and games.