run-crons
run-crons (2008) is a Gentoo-specific (though, probably, distro-agnostic) shell script for auto-scheduling user cronjobs via user-local ~/etc/cron.hourly/, ~/etc/cron.daily/, ~/etc/cron.weekly/, and ~/etc/cron.monthly/ directories. This script is authored by Leyli Cecil; licensed under the GNU General Public License; and publicly, freely downloadable:
This script reliably forks the 2005-03-08 version of Gentoo‘s /usr/sbin/run-crons.