JTablePro is an extension to the standard JTable. It allows the user to collate rows and give header rows for each group of rows.
It behaves exactly like the Microsoft Outlook 2003 inbox table. Column headers can either contain images or text. Sorting can be done on either column types. Clicking on the column header sorts the column asc and desc. The user simply implements certain interfaces and extends abstract classes to make it work.
It also has a Calendar type of column which shows a drop down...