Mike Kruckenberg posted recently a tip he found to create easy text bar charts using the REPEAT function, that he found at:
http://www.squarebits.com/blog/2006/11/generate_simple.html
Today I stumbled across this link:
http://www.webcheatsheet.com/php/dynamic_image_generation.php#diagram
Which, using PHP, creates a graphical bar chart using the data in a MySQL database and a small bit of math.
Both are very neat!