Ask HN: Whats a reliable cron service?

Hi HN,

I'm building an app and thinking of using phpfog as my hosting provider but they lack cron job features so I was wondering if anyone had any experience with cron jobs as a service providers?

What I need it for is to update and cache rankings every 5 minutes instead of every page execution.

I was hoping anyone had any experience they could share, also preferrable free but willing to pay a monthly fee but would rather not pay per cron execution as I hope to run this cron every 5minutes

Thanks a lot