Project Shield is not a mainstream service yet, just an idea that Google is trying out, but still, I think it’s worth a mention.
Project Shield is an initiative launched by Google Ideas to use Google’s own Distributed Denial of Service (DDoS) attack mitigation technology to protect free expression online. The service allows other websites to serve their content through Google’s infrastructure without having to move their hosting location.
There is also a video:
[youtube=http://www.youtube.com/watch?v=wmTvv8ISwPA]