Google today is showing the Missing Link - nothing to do with SEO though, it's 'Ida' the fossil discovery. Kudos to Google for changing the homepage logo so quickly - what an amazing find!
Google changes homepage logo to celebrate 10th birthday
Google creates Lego homepage logo to celebrate Lego's birthday
Google changes for International Pirate Day
Google changes homepage logo to honour the Queen
Google goes black for Earth Hour
Google changes logo for the Olympics