BlockAID (or PeerDNS) is a public DNS service that aims to get around domain seizures.
When the U.S. Immigration and Customs Enforcement (I.C.E) seizes a domain name, the website is not taken offline. Instead, DNS servers send web browsers to the wrong web server, which results in a message from the ICE about the domain seizure (shown below.)
BlockAID gets around this problem by directing users to the correct server.
It is not capable of detecting if a domain has been seized automatically, but if the owner or operator contacts BlockAID, they can help. The use of BlockAID is free to all users, and DNS requests are not logged by the service.
Click here to read a guide on setting up BlockAID on Windows or Mac OS X.