Kamal Hosen

pixelplugin

This plugin will easily give the user the option to follow the category or tag of his choice. This is basically a widget based plugin, it will work from the time you activate your tag / category follow widget after you install the plugin. One of the conditions for this to work is that the user must be logged in.

Follow Tags & Categories

User's can follow specific Tags or category and show only those tags/category posts.

Skysa

Simply set the Twitter account you want users to follow; then, when they click the Twitter Follow button at the bottom of your site, they will start following your account on Twitter. You can optionally set to display your current followers count next to the Twitter follow button and also the language of the Twitter follow button text.
http://www.youtube.com/watch?v=Zj1uGXX2xrk&hd=1 
<a href="https://wordpress.org/extend/plugins/tags/skysa-apps" rel="ugc">More Skysa App plugins</a> -|||- <a href="https://wordpress.org/extend/plugins/skysa-official/" rel="ugc">Skysa App Bar Integration plugin</a>

Skysa Twitter Follow App

Allows your site visitors to follow your twitter account with one click, without leaving your sitet.

Follow Tags & Categories vs Skysa Twitter Follow App