Here is a service I always want: I'm in a prison cell. I cannot get out until the prison evaluates my progress on a target that I submitted for the service (say fully read a tech book and create a demo). I'd also setup a default end date which will be evaluated and confirmed by the prison. If I don't complete the target before the end date I get double charged for each day and food becomes shittier. Of course there is a hard deadline to make sure my bank account still exists afterwards.