Graphing games
Search for Mummy Chase (from classzone.com)
http://www.math.com/school/subject2/practice/S2U4L3/S2U4L3Pract.html
http://www.regentsprep.org/Regents/math/ALGEBRA/AE3/answer2.htm
http://hotmath.com/help/gt/genericalg1/section_2_3.html