Nice!

I would indeed sleep better if the service monitored my cron jobs. But I would sleep even better if I knew you were making some money from this, because this gives you an incentive to keep providing the service.

For instance, you could offer a paid plan for users with >N/day requests or something like that...

Not sure if you want to go there or not (and I am not currently in the market for such a solution as I have solved my need with a proprietary solution), but the fact that there is no paid plan lowers my expectations of the service.

EDIT: clarified my point.