Number Theorists' Home Pages - Part of the Number Theory Web.

Structure Theorists - List of logicians, algebraists, categoricians, ... working on mathematical structure.

ASL members - List of web pages of Association for Symbolic Logic members. Maintained by Herbert Enderton.

Graph Theorists - Comprehensive graph theory listings maintained by Daniel P. Sanders. Includes nearly 600 people (both dead and alive), some of their publications, students, and home pages.

Web Pages of People in Probability - Part of the Probability Web.