This video introduces our new Similar Images feature. Similar Images allows you to search for images using pictures rather than words. With the similar images feature, most images have a link below them that lets you find other images like them. There’s no need for you to refine the text of your query. Your new results will be tailored based on whatever image you select.
Visit: Google Similar Images
Everyone knows that Google Image Search sports a drop-down menu for 
filtering results by small, medium, large, and extra large sizes, but if you’re looking for the perfect wallpaper, for example, the imagesize operator is even better. Weblog Design Live uncovers the undocumented search operator (that’s also new to us) and demonstrates how to use it. Just use the imagesize operator followed by the WidthXHeight in pixels, like so:
Here’s an example: [imagesize:640×480 muffin] finds 640px x 480px images related to muffins.
As the post points out, the imagesize operator is perfect for finding wallpapers that are the perfect fit for your screen.