CSP Archive - Contains information relevant to the process algebra CSP (Communicating Sequential Processes.)
Formal Methods Europe (FME) - Worldwide association bringing together researchers and practitioners in formal methods developing computing systems and software.
Petri Nets World - Provides information on the International Conferences on Application and Theory of Petri Nets, mailing lists, bibliographies, tool databases, newsletters, and addresses.
WWW Virtual Library: Formal Methods - Points to sites containing information on formal methods, useful for mathematically describing and reasoning about computer-based systems.