Once Google has finished snowing all over your screen, you can use your cursor to "skate" across it and leave tracks, or scrape off the ice to reveal what's underneath.
If you like lights, try typing "Hanukkah" into google and you'll be treated to a string of lights in honour of this festival of lights.
These are known as "easter eggs" by google - treats you only find by hunting. If you find more, let us know!