1) Google home page is simple because of the fact that the founders didn't know HTML but they always desired a quick and good user interface.
2) One of the best feature "I feel lucky" is very rarely used and known by the users. But when Google tried to remove that button then it was noticed that users weren't comfortable with that, and the button was back at its position.
3) Google user's experience has improved a lot after the invention of spelling checker. That is "Did you mean..." feature. This was the major reason for the increase in user traffic.
4) People from Brazil just love to spend their time on Orkut. Orkut was the invented and got popular in many countries but now people are switching to Facebook or Twitter or Google+. But it is still popular in Brazil.
5) Google has the largest number of employees working as translators as compared to any other company in the world. And interesting fact is that they aren't aware of this, Google just monitors how these users interacts with the new user interface.
6) Google experiments the latest features with a small network, for example abc@example users will have a chance to get the experience of the latest features of existing apps or new apps.
7) Initially Google was going to be named as "Googol", but many investors found it as spelling mistake and requested to change it to "Google" to the founders.
8) Gmail was not launched for public for nearly two years. They found that there are six type of email users and Gmail was made for all.
9) Google takes feedback seriously and they do act according to it.
10) Google employees are encouraged to work on their own projects for more than 20% of their working time. Google News and Orkut are the outcome of such working model.