Akhil Jain: Personal page of a University of Chicago Financial Mathematics Graduate.
Huiqiang Jiang: Research interest: partial differential equations, calculus of variation, and geometric measure theory.
Jaffe, David B.: Whitehead Institute/MIT Center for Genome Research. Computational biology. Coding theory database and links.
Johnson, Bob: UK mathematician providing material on mathematics courses and research including Fibonacci numbers and chaos theory.
Jorgenson, Jay: Includes profile and research interests.
Junichi Yananose: Mechanical puzzles and transformable polyhedra.
Juno and her Peacocks: A site about math; graduate and professional life; interesting anomalies; resources and links to things mathematical such as Math Camp.