Instituto Latinoamericano de la Comunicacion Educativa
Red Escolar: Caminos Diferentes
In Spanish. This page has a series of "little problems" of recreational algebra. Try to solve them using algebra or common sense and have fun.
University of St. Andrews (UK)
University of St. Andrews: Nicholas Chuquet
This site from the University of St. Andrews provides a biography of mathematician Nicholas Chuquet, who was the first to use negative numbers as exponents and coefficients.