Get-ScheduledTask
This isn't super pretty, but it shows all the scheduled tasks on a system and the domain account they're running under:
Get-ScheduledTask | select-object -ExpandProperty principal
Stealing tickets with scheduled tasks
While not directly related to Get-ScheduledTask, I wanted to mention that the brilliant CCob gave me an idea (source: BloodHoundGang) for stealing tickets with a scheduled task sent to run klist.