Nicolas Bouliane

This plugin will display the administrator’s email on the dashboard so other users can easily contact him.

Dashboard Admin Email

Displays the administrator's email on the dashboard

genkisan

<ul>
<li>easily switch on and off through Admin Options</li>
<li>display message without editing theme files (above 1st post or through widget)</li>
<li>display different message to different roles/users</li>
</ul>
Demo: 
<a href="http://ericulous.com/2007/03/09/genki_announcement/" rel="nofollow ugc">Plugin Details & Demo</a>

Dashboard Admin Email vs Genki Announcement