www.jfree.org

I clicked on the download link on the JCommon page, and it took me to the JFreeChart project at SourceForge. Search for jcommon there turned up nothing.

The new interface at SourceForge makes it a little harder to see. When you get to the JFreeChart download page, scroll right to the bottom and you'll see a JCommon entry. Click on the little '+' symbol, and it will open up and show you the files.