Shodor Education Foundation
Shodor Interactivate: Bar Graph
A wonderful tool and learning experience using a bar grapher. This site contains an interactive bar grapher and much more! Follow the "What?" link to get to classroom resources such as problems and explorations.
National Council of Teachers of Mathematics
Nctm: Illuminations: Bar Grapher
A computer applet that will draw any bar graph with student's data input.