Allows users to limit the number or words that are displayed when they want the excerpt or content of a post to appear.
This plugin limits content on front or archive page after set number of words, add gettexted more link to the end of it , pull out only wordpress allowed html tags, check if any xhtml tag is unclosed and close it, take and resize first image from the post.
In your theme file find
<?php the_content('Read more...'); ?>
And replace it with
<?php content(100, __('(more...)')); ?>