One of our clients recently got infected with a TeslaCrypt variant and I decided that I've had enough and started researching ways to prevent similar things from happening in the future.
We came across Microsoft's free File Server Resource Manager role feature in Windows Server, which allows you prevent files matching a certain filter (called "File Screens" in FSRM parlance) from being written to the server. While it's certainly not the end-all/be-all solution, it's proved to be fairly adept when kept up to date.
So that's what I did - I built a site that allows people to stay up to date with the latest file screens for free.
The site is here: https://fsrm.experiant.ca and I am absolutely open to all suggestions, and there's a space near the bottom for submitting file screens that aren't already in the list.
Please let me know what you think.