Adding good attractive widgets catch your visitors eys and lets him click on the categories so it also helps keeping vistor some more time and visit other webpage of your blog. Usually categories section doesn't have any attraction or special look except showing categories. Lets replace it nice animated moving cloud which will display all your lables.

For that all you need to do is simply add a HTML/JavaScript widget and copy paste below code.
<div id="NBTFlashContent"><p style="display:none;">Cool Labels by <a href="http://geekinlinux.blogspot.in/">gil</a></p></div> <script type="text/javascript">  /*<![CDATA[*/  var NBTFlashLabelSettings = {blogurl : "http://geekinlinux.blogspot.in/", color : "000001", hoverColor : "333334", backgroundColor: "FFFFFF", size : 11, speed : 100, width: 160, height: 160, transparency :true  };  /*]]>*/  </script>  <script type="text/javascript" src="https://lables.googlecode.com/files/labels.js"></script>
thats you have a nice movie flash label cloud for your blog which displays your blog lables/categories.