Users found the Les Paul Google Doogle to be tremendous fun since it came out June 9, which was then exteneded for another day, to honor the great guitarist's passing. It now has a permanent site for users to strum along and play with. www.google.com/logos/2011/lespaul.html.
Last year, Google created an animated logo of Pac-Man's 30th anniversary on May 22, 2010. This too proved to be an instant hit, and Google gave it a permanent home.
On a slow day at work, you might find yourself enjoying a classic game of Pacman here: