Every time you modify a post slug, add a new post, rename a category, or otherwise modify any of your post and page permalinks, jadedcoder Sticky Permalinks (jcsp) will keep a copy of the original permalink along with the post or page it originally led to. If anyone tries to access the old URL, they will be redirected right to the new one, no matter how many times you’ve changed it.
If you re-use a URL that has already been used in the past, its copy will be replaced and it will safely link to the new article instead.
Don’t throw away valuable URLs! This plugin lets you re-organize your site as many times as you want, without risking traffic loss.

jadedcoder Sticky Permalinks

Keeps a history of your permalinks no matter what changes you make on your site, and redirects old links to the new ones.

Vladimir Prelovac

WP Digg This is a plugin that adds a Digg button, but with a twist. Instead of adding a Digg button to all your posts, WP Digg This plugin selectively adds the button only to posts you want.
To add a digg button just add a ‘digg’ custom field with value ‘1’.
WP Digg This can display digg button on your single pages but there is an option to show them on home and archive pages as well.
Plugin by <a href="http://www.prelovac.com/vladimir" rel="nofollow ugc">Vladimir Prelovac</a>.
<h3>License</h3>
This file is part of WP Digg This.
Category Search is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Category Search is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with Category Search. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

WP Digg This

Provides an easy way to selectively add Digg button to your posts. Use 'digg' = '1' custom field in the post to promote it.

jadedcoder Sticky Permalinks vs WP Digg This