The plugin I am going to cover in this post, is an existing one which has been brought up to coding standards; Icons.
This plugin includes 1,000 small icons which can be included anywhere on a site using the Icon shortcode. The Call-out Boxes plugin integrates with this plugin to easily allow icons to be included in the call out boxes.
Check out this post on my demo post to see this plugin in action.
The plugin can be downloaded via my Development site.