If it wasn't for the "this service would need access to my email account creds and therefore to all my mail" showstopper...
A distributed service where a group of people all have their own service to "ping" their personal "important accounts", and which accept federation with friends or other users of the service, so if your server/vps/serverless/whatever platform instance goes down your pings still happen from your connected servers.
Elevator pitch: "Like IPFS, but for cron jobs calling curl."
