Is there a way to view JUST the rendered image while making the interface disappear (a la Photoshop fullscreen)? I want to see literally only my rendered pixels and zero Blender interface things. Thanks!
actually the whole interface can be removed from ANY view, not only the Image Editor. Place your mouse cursor over the area in question, then hit Right Alt+F10 (maximize view and remove interface) and then Alt+F11 (remove title bar and also task bar on Windows or dash on Linux). To get back, you can use the same keystrokes, or move the mouse cursor in the top right corner of the window, until an icon appears.
Not exactly with zero interface, but if only the info bar is little enough then you can change the viewport to the uv/ image editor:
Then select render result from the list of available images.
If you want to get the properties panel off- screen, then just press Shift+Spacebar to toggle it and clean up the view. You can pull the footer down as well if you wish.