Add a Read More link to the_excerpt() in WordPress

To remove the default […] marker at the end of an excerpt and add a Read More link add the following code to your theme’s functions.php file

function new_excerpt_more($more) {
     global $post;
     return '<a href="'. get_permalink($post->ID) . '"> Read More...</a>';
}
add_filter('excerpt_more', 'new_excerpt_more');

Tested with WordPress version 3.3