Exit node operator here, had to login to address your comment. One of the bigger advantages of a hidden service is that you can't be sure who's hosting it and

Exit node operator here, had to login to address your comment. One of the bigger advantages of a hidden service is that you can't be sure who's hosting it and where. They're great for hosting websites but do nothing for allowing access to other services. If you're worried about trouble from running an exit node you could contribute by running a relay or a hidden bridge which would be way more useful than a hidden service. I've actually been contacted by the Michigan State Police in a child porn investigation and after explaining that I run a TOR exit node and have no ability to help in their investigation the officer I talked to was quite pleasant. I've heard nothing about it since then. There are several news outlets that run hidden services for whistle blowers and people in danger or unable to speak openly so your idea isn't without merit but it does require pre-planning to be of any use. If you've got no way to communicate the existence of your service to people before they need it, it'll be of little use.