Gmail - Hit inbox zero in gmail on your iPhone and get a smiley sunshine icon and a message to enjoy your day.
Xirrus - If you’re an existing customer and your public IP address is on file, the homepage is customised to reflect your company name when visiting from your corporate network.
/via Gary Lee
Google - When looking at the wind speed in weather forecasts, the size of the arrows gets larger for stronger winds.
Harvest - When you have a timer running in the past, the warning hails your time-traveling feat with two references to Back to the Future.
/via Lior Zur