title: ggplot2 - highlight min/max bar
body: <p>Without adding an extra column to the data.frame, is there a built-in way to highlight the min/max bar?  In the following example, I'd like the Joe bar to be green (max) and the John bar to be red (min).</p>
  
  <p>I'm sure this has been asked before, but I couldn't find when searching:</p>
  
  <pre><code>data= data.frame( Name = c("Joe","Jane", "John") , Value = c(3,2,1) )
  ggplot(data=data)+geom_bar(aes_string(x="Name",y="Value"), stat="identity" )
  </code></pre>