Virgle : The Adventure Of Many Lifetimes. http://googleblog.blogspot.com/2008/04/announcing-project-virgle.html http://www.google.com/virgle/index.html
Other Pranks BigG did in the past:
Gmail Custom Time; Be on time. Every time. https://mail.google.com/mail/help/customtime/index.html
Google gDay : Search tomorrow's web, Today. http://www.google.com.au/intl/en/gday/index.html
Gmail Paper. http://mail.google.com/mail/help/paper/more.html
I have to say: when they want to do it, they do it well!