University of Colorado
University of Colorado: Ph Et Interactive Simulations: Least Squares Regression
Create your own scatter plot or use real-world data and try to fit a line to it. Explore how individual data points affect the correlation coefficient and best-fit line.
McGraw Hill
Economics: Econ Graph Kit
This is a graphing tool for economics students that allows you to draw curves, lines, tick marks, etc. Also gives students the ability to label the axis and print the graph. Sample problem included.