A large collection of cryptarithms and alphametics, including cryptarithms from the journal Sphinx, a Primer on Cryptarithmetic, books, and links to other collections of alphametics on the Web.
New version of the classic puzzle using row/column/quadrant permutations to display symmetries of graphic designs. Has link to a site on the underlying mathematics (Diamond Theory).
The annual journal of the Archimedeans, the mathematical society of the University of Cambridge. It regularly contains articles on recreational mathematics.