Champ Math Contest http://www.geocities.com/champmath/
Purple Math - great lessons available online for many of the topics covered in the grade 10 curriculum http://www.purplemath.com/modules/index.htm
Cool Math http://www.coolmath.com/algebra/
Math Homework Help http://www.oaklandcc.edu/iic/iicah/ah_www_mat_alg.htm
Stuck on a problem ... try WebMath http://www.webmath.com/