We knew you could drag and drop images into Gmail messages, but it turns out you can also just copy and paste them, which in some situations is even more convenient.It doesn't get much simpler than this: just right-click on any image, hit "copy image", and then head into Gmail and hit Edit > Paste (or Ctrl+V, even). If you're using Chrome, your image will pop right into your message and you can send it as normal. It's nice if you have an image open in one tab and don't want to move your windows around just so you can drag and drop—two clicks and a keyboard shortcut and you're on your way.
Note that you can paste images into Gmail in Firefox too, but it won't work correctly — the images will show up distorted on the other side. So even though it may appear to work, it actually doesn't. Hopefully we will get to see this functionality in both browsers soon.