Read More Inline free WordPress plugin

Allows you to use the ‘read more’ quicktag to hide the content following it and instead show a ‘read more’ link. When the user clicks the link, they see the rest of the content right after the link, without leaving the page. It replaces the default behaviour (linking to a full version of the page/post) and is a way of keeping the initial page content short, but allowing users to read more if they want to, without having to leave the page. It’s superlightweight, works on the fly using jQuery and can be activated and deactivated without making any changes or leaving any trace in your WordPress installation.