Joseph Pearson of Make Believe has coded a topographic page layout bookmarklet that shows the layout of a webpage. Basically, it recolors the elements of a webpage, giving more deeply nested elements a lighter color. The effect is that you can see the "topography" of a webpage, which makes it that much easier to detect unclosed divs or for those situations where something is wrongly positioned but you just don't know why. Another of those must-have web development bookmarklets.