I believe having Table of Contents for lengthy posts and pages would be really helpful. Some authoring tools such as Wiki and Twiki automatically create Table of Contents based on page headings and a few plugins can make this happen on Word Press too.
One such plugin that is easy to use for WordPress is Table of Contents Plus (external link).
All a user needs to do is install this plugin and activate. Based on the heading structure, plugin automatically creates Table of Contents. User has flexibility to place Table of contents either before or after the page content.
In order to have the plugin generate Table of Contents, it’s essential that author uses HTML heading mark-up.