Project-Euler-Answers is a project mainly written in PHP, it's free.
This is my repository of answers to Project Euler Problems - Good place to see coding samples across a variety of languages.
What is Project Euler?
Project Euler is a series of challenging mathematical/computer programming problems that will require more than just mathematical insights to solve. Although mathematics will help you arrive at elegant and efficient methods, the use of a computer and programming skills will be required to solve most problems.
The motivation for starting Project Euler, and its continuation, is to provide a platform for the inquiring mind to delve into unfamiliar areas and learn new concepts in a fun and recreational context.
Please see the Project Euluer site at http://projecteuler.net/