Here’s the ones I think will be most useful or fun for you:
Set a timer, optionally full-screen: Just search for an amount of time, followed by the word timer, eg 25 minute timer (good if you’re a fan of the Pomodoro Technique!)
Google NGrams lets you see how usage of certain words in books has changed over time, from years 1500 – 2008.
See how to pronounce huge numbers by searching for the number and then typing =english, eg 1234567890=english produces “one billion two hundred thirty-four million five hundred sixty-seven thousand eight hundred ninety”
Google Trends lets you see what the top searches are right now:
You can also enter a search into Google Trends to see how a search term has trended over time: http://www.google.com/trends/explore#q=awesome