Remi Corson

This plugin helps admins to easily create admin notification inside the WordPress administration.
You can choose many options and decide how and where to display the notifications.

Easy Admin Notification

Tested up to 3.3.1 Stable Tag: 1.4 Adds the ability to create easily notification in the admin panel

mrsajith

You can set your message /news here.You visitors can now see your announcement. The Plugin is created with light window support. The animated effect on announcement will give a pleasant effect for your blog/website. It will be displayed only one time for a particular user . The plugin is created with cute design and animation. It will never interrupt your blog reader.
Features:
<ul>
<li>Navigation: You can navigate your reader into a particular event</li>
<li>Message Passing: You can announce any event information here</li>
<li>Html content: You can add images, links, color just like a post (RTE). </li>
</ul>
For Example and Details Visit : http://www.sajithmr.com/wordpress-announcement-plugin/
My Technical Blog is : http://www.sajithmr.com/
<h3>Arbitrary section</h3>
If you have any queires / complaints regarding this plugin, please feel free to mail me at admin@sajithmr.com. Thank you
See my blog for technical updates <a href="http://www.sajithmr.com/" title="Technical Digest" rel="nofollow ugc">http://www.sajithmr.com</a> .
<blockquote>
Use announcement and improve your website quality. Happy Blogging
</blockquote>

annouoncement

Do you wanna inform any important news or message to your readers ?  You can use this plugin.

Easy Admin Notification vs annouoncement