Google has a robots.txt file that lists all paths that can't be crawled by Web spiders, but there's also a humans.txt file which tries to show that Google is not all concerning bots and algorithms
"Google is built by a large group of engineers, designers, researchers, robots, and others in many different sites across the globe. It is rationalized continuously, and built with more tools and technologies than we can shake a stick at. If you'd like to help us out, see google.com/jobs."
Google's Tim Bray connected to this text file and the Google Jobs Twitter account made it more popular.
YouTube's robots.txt file has lately added a humorous comment: "Created in the distant future (the year 2000) after the robotic rebellion of the mid 90's which wiped out all humans.