Images that break out of the box are a popular effect. This is easy to achieve with pseudo-elements. No need for images in the markup, nested elements, or empty elements.
Depending on the look you're after you can absolutely position or float the pseudo-element. This technique gives you a lot of flexibility over the positioning of presentational imagery. They can be part of the normal flow; or content can flow around them (float); or they can be removed from the document flow entirely and positioned from any side (absolute/fixed positioning).
This example floats the pseudo-element so the main content's text will wrap around this image.