- History of Math site
- Biographies of women in math
- A bunch of mathematical quotations
- a collection of definitions of what mathematics is
- mathematics of origami -- Tom Hull's pages

- a website with a variety of cryptography related puzzles
- Enigma-like cipher challenges and information on world war II crypto (Enigma)
- elliptic curve cryptography tutorial
- Handbook of applied cryptography

- Ron Knott's super informative site
- The Fibonacci Association