The magic of <div style="clear:both">

As I am deep in the innards of the HTML and CSS of the web site I'm working on, I've found that <div style="clear:both"></div> is a really useful tool. It basically sets an invisible horizontal rule for starting a new section of content. Funny thing is that you have to have the explicit closing tag for it to work; <div style="clear:both" /> won't do it.