This site from MathWorld provides a general overview of frequency distribution, complete with a bar graph and explanatory text.

[Free Registration/Login Required] Students draw conclusions and engage in tables and charts involving cumulative frequency; a wonderful review of student's knowledge.

Richland Community College provides a glossary of many terms that are needed in order to understand statistics graphs and charts. Each of the types of charts is quickly explained in terms of what it is most effective in displaying.