Shameless self-promotion: I built Eventline (see my profile) precisely because I just wanted to schedule and run code in various environments, manually or in reaction to various events, without the complexity that goes with specialized tools.

It gives you a pretty flexible job system, identities (secrets), monitoring, notifications, a web interface, a command line tool and a HTTP API. You can build lots of things above it.

Do you have specific use cases in mind ?