This is the same as [{% widthratio %}](http://docs.djangoproject.com/en/dev/ref/templates/builtins/#widthratio) but when the given value is greater than the max_value it just uses the max_value. This way the result is never greater than max_value. It also returns max_width if the max_value is 0 instead of returning a blank string. Usage example: {% smart_widthratio this_value max_value 100 %}
The {% widthratio %} template tag is under appreciated! Here, it's combined with CSS to create a bar graphic for the results of an election (this example comes from [this page](http://flickr.com/photos/postneo/405239750/in/photostream/), but has been modified slightly for simplicity's sake). The widthratio tag can be used to create all sorts of graphs and charts, as well as things like tag clouds. Here, we pass it the number of votes for a candidate, the total number of votes in the election, and the integer 190, which is the width, in pixels, of a "full" bar on the bar graph. In other words, 100% = 190 pixels. It works great!