OStatic

I'm using command+shift+4 extensively for taking screenshots but its excruciatingly painful because it keeps saving the screenshot as an image file on the desktop - then I got to go find it, copy it, and paste it on the keynote (which is great, btw!) slide. Then I have to go back and find that file on the desktop and delete it to avoid cluttering my desktop with random screenshots. Is there any way I can just save the screenshot to the clipboard like in Windows and simply paste that in whatever app you choose??