URL shorteners are a great idea, but for very limited use cases. I think they only make sense when run by a particular service for use with that service's URLs,

URL shorteners are a great idea, but for very limited use cases. I think they only make sense when run by a particular service for use with that service's URLs, like t.co or db.tt, and live and die in tandem with the underlying service. General purpose URL shorteners are just time bombs waiting to go off. They'll die and break all of their captive URLs or they'll realize they need to make some money and do something like this (or much worse). There's no third option.