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>

Genki Announcement

Mstoic Themes

This plugins enables media uploads by contributors. By default, contributors can not upload media files, this plugin allows them to do just that.

Genki Announcement vs Contributors Media Upload by Mstoic