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.

Phoenixheart

“Digg This O’ Mine” is a plugin that allows you to place the famous <a href="http://digg.com/tools/integrate" rel="nofollow ugc">“Digg This” button</a> at the end of your posts, pages, or anywhere at your choice. While it will run out of the box, it has several options that can be used to custom the button to fit your needs:
<ul>
<li>Automatically add “Digg This” button to your posts (yes/no). Default is set to Yes.</li>
<li>Automatically add “Digg This” button to your pages (yes/no). Default is set to Yes.</li>
<li>Background color around the button. The option is provided with a handy color picker. Default is “#ffffff” (white)</li>
<li>Skin of the button. Digg offers 2 skins: Default and Compact. Default is set to “Default” 😉</li>
<li>Open the Digg link in a new window (yes/no). Default is set to No.</li>
</ul>

Digg This O' Mine

Place a "Digg This" button at the end of your posts, pages, or anywhere at your choice.

jadedcoder Sticky Permalinks vs Digg This O' Mine