Content Enhancer

This powerful plugin allows you to insert HTML/Javascript code into your WordPress post’s content in a variety of different ways.

Using this plugin, you can specify pre-defined HTML code to be displayed at the top and bottom of all your posts, saving you valuable time. Merge fields let you pre-define HTML/Javascript that you can use anywhere in your post. For example, using [my_twitter] you can include an HTML link to your twitter account, anywhere in your WordPress post.

More more info and screenshots, please see: Content Enhancer homepage.