RazielKanos

This plguin simply adds a CSS code into your Admin Dashboard and hides most of the nagging messages telling you 
that you should activate or register other GPL 2 Plugins.
It doesn’t add any functions other than adding the CSS code, so there should be no trouble with other plugins you are using.

WP Remove Admin Register Nag

This plugin removes the reminders that you should register plugins you got by a theme for example

scribu

Whenever I visit my site’s dashboard, the first thing I see is the bold red Spam count.
Instead of wasting time deleting spam comments, I prefer to let Akismet do that automatically, so I don’t need to see how many spam comments there are.
This little plugin simply hides that part.
Links: <a href="http://scribu.net/wordpress/hide-spam-count" rel="nofollow ugc">Plugin News</a> | <a href="http://scribu.net" rel="nofollow ugc">Author’s Site</a>

Hide Spam Count

Hide the annoying spam count from the Dashboard.

WP Remove Admin Register Nag vs Hide Spam Count