Here’s a cool use for Ajax – an active table were users can edit and add columns into a table in HTML.
The ActiveTable library creates an editable HTML table from a MySQL database table.
Link: AJAX ActiveTable – Jonathan Diehl’s Wiki
Here’s a Demo of Ajax Active Table (This loads from the author’s site in an iframe and may take some time to load):

stefan on August 9, 2006
Wow, this is really great and makes it very useful to use Ajax.
jubal on February 5, 2007
it requires PHP5+ and MySQL4+ which is not always available with cheap hosts… many refuse to update
vinu on February 5, 2007
True. Many hosting companies refuse to upgrade to php5. If your hosting company is not flexible enough, then there’s no point continuing with them.