WikiSh can be used as an extremely powerful forms processor without writing a line of PHP code. The forms themselves are made using normal PmWiki.Forms but then any validation and the actions taken during processing the form are accomplished using wikish.
Note that for security purposes WikiSh defaults to having NEITHER read NOR write privilege on ANY PAGES! You must explicitly give read/write privilege via the various $Enable... variables in config.php and via the SecLayer configuration. See WikiShConfig for more details.