Alphametics Page
Explains this combination of arithmetic and words, and provides examples of several different types.
Nick's Mathematical Puzzles
A collection of an assortment of problems to try to solve, with hints, and solutions. Includes daily update feed link.
The Exhibitionists
Interactive, practical math puzzles relating to the management of a museum exhibit. Sponsored by the (British) National Museums Liverpool.
Torsten Sillke
A professor presents his extensive collection of puzzles which use counting, arithmetic, algebra and whole numbers.