Chron Jobs

Building on a previous post, I'd love to see a way to schedule "Chron" jobs - routines that run on a time schedule as opposed to on add/validate/submit. One of my apps tracks project schedules and I'd like to build a function that sends an email when a task due date is overdue. This currently is only possible if you edit the record - something which is unlikely. Scheduling the ability through an "On Schedule" where it checks a field every X minutes or hours would allow me to review all records for set criteria and take actions even in the background.