Original Link: http://37signals.com/svn/posts/2979-css-tip-spot-unsized-images-during-development

Neat trick…

Have you noticed that software feels cheap when UI elements move around on the screen without notice? Web applications are particularly vulnerable to this problem. Browsers give image elements a default size if they do not have explicit width and height attributes. Once these images have loaded, they expand or contract to their full size, causing all other elements on the page to reflow in response.