algebra
http://www.mathwarehouse.com/algebra/linear_equation/systems-of-equation/index.php
http://www.mathplayground.com/SaveTheZogs/SaveTheZogs.html
http://www.ltcconline.net/greenl/java/BasicAlgebra/Linegraph/LineGraph.htm
http://hotmath.com/help/gt/genericalg1/section_5_2.html
http://algebralab.org/lessons/lesson.aspx?file=Algebra_LinearEqSystems.xml
http://www.regentsprep.org/Regents/math/ALGEBRA/AE3/PracAlg.htm
Algebra II Topics
http://www.bgfl.org/bgfl/custom/resources_ftp/client_ftp/ks2/maths/percentages/index.htm
(percentage game)
http://www.mathplayground.com/percent_shopping.html
Geometry
http://www.onlinemathlearning.com/geometry-math-games.html
scroll down to Angle Games
Triangle Congruency
http://www.algebralab.org/practice/practice.aspx?file=Geometry_TrianglesandCongruence.xml