Calculators
Free Graphing Calculator: http://wabbitemu.org/ - this is a graphing calculator that should work like the one that you use in school (ti 83+, ti84, ti84 silver edition). Tutorial on how to download: http://www.youtube.com/watch?v=dhxKEc1MWyw
Graphing Calculators for Mobile Devices
www.coolmath.com/graphit/index.html
www.homeworknyc.org/toolbox/calculator.cfm
Graph Paper
Useful Websites