http://www.math-play.com/Inequality-Game.html
http://www.coolmath.com/algebra/algebra-practice-solving.html
http://www.quia.com/rr/438640.html
http://homepages.ius.edu/dcureton/lessons/hunt.htm
Basic rules: http://www.sosmath.com/algebra/inequalities/ineq01/ineq01.html