JET4 Content Areas allows you to create content which you can drag into a widget area, show in your template files, or place into your other posts and/or pages.
This plugin also has many hooks, including filters for almost everything as well as actions so you can modify its behavior to fit your needs painlessly.
Plugin’s Official Site
JET4 Plugins (http://jet4plugins.com/content-areas)
Please comment here for issues/complaints/suggestions.