The Inca Empire or Inka Empire was the largest empire in South America. It was the last sovereign political entity that emerged from the Andean civilizations before conquest by Spaniards.
Gmail predicts which emails might be of high importance to you so it marks them as important with a yellow icon. If your inbox ends up full of so called important emails, this is how you disable this feature.
Windows 7 have a nifty feature which combines the windows of opened applications under the same taskbar button. If you don't like it you can always turn it off.
A very useful Facebook debugger tool where you can check how your webpage looks like on Facebook when like button is pressed, without actually pressing the like button.