The best WordPress "Read more" plugin to help you show or hide your long content.

Scans posts for picplz links and expands them to show the image.

Small and efficient plugin implementing dynamic "Show more..." links. Just use the [showhide] shortcode, there is no addition to the backend.

Twitpic Expander scans posts for twitpic URL's and automatically expands them and shows an image.

Scans posts for Youtube URLs and expands them to show a playable video at the end of the post.

Expandoo expands images when they are clicked, much like a lightbox, but without opening anything new.