Don't print $title on certain content types
There is also a module for this:

Exclude Node Title


  Info
  
  This module handles a very simple functionality, decide whatever to
  exclude a node title from full node page or node teasers.
  
  It provides a checkbox on node-edit pages for easier exclusion.
  
  Also provides the option to hide all titles of a certain Content type.
  From the administrative interface you can select a content type to
  hide title for.


And if you have Display Suite installed then this article explains how to do it with that module:

Hide “Page Title” quickly using Display Suite in Drupal 7


  This is something that is so simple to do, once you have figured out
  the steps to get to the right little click boxes to appear. I wish
  that it were more intuitive to find, but for all those who struggle
  with “hiding” the page titles, Display Suite makes it really easy to
  choose to hide the page title for a specific Content Type or for a
  particular Node.