Special hidden google pages that are not visible to everyone

There are some special works of Google, that are known but to a select community of people. They are the  special  or hidden or lesser known of the Google pages, and are worth having a look at. Check them out !

Google pages not visible to everyone

Google Moms
Rare Google Beta Logo and Google Holiday Logo’s
Google’s Metaplex
Google Heart 1 & Google Heart 2
Google Newsletter
Google’s Search Statistics and Tribute.
Google Doodles