Schedule PHP scripts to run on a web page access:
queue an unlimited number of scripts with per-page scheduling;
queue scripts for all pages within a directory with directory-wide scheduling;
substitute backup scripts to run in the place of PHP tagged "under maintenance" -- the backup script instantly replaces the maintenanced PHP, across the site;
schedule scripts in layers, then reuse these layers, to eliminate repetitive PHP;
experience the system attracting such testimonials as: a viable option to CRON, a great tool.
As seen on Hotscripts and the PHP Resource Index.