An ancient screen shot of the CERL PLATO system's welcome page from 1975.

Long before Google was customizing their home page to celebrate observances, holidays, and such (like they are doing this week with the 2010 Winter Olympics), at a time when Larry and Sergey were still too young for kindergarten, PLATO's welcome page would be customized for various holidays like Christmas, 4th of July, Valentine's Day, Halloween, and Thanksgiving.