Matt Martz

Remove and restructure the ‘Howdy’ line. Props to Ozh for <a href="http://planetozh.com/blog/my-projects/no-howdy-a-plugin-for-wordpress/" rel="nofollow ugc">No Howdy</a>.
People have always seemed to complain about the ‘Howdy’ on the admin pages. I personally don’t care about the use of the word but think that the ‘Howdy area’ could be more functional and user friendly.
<h3>Usage</h3>
<ol>
<li>Just activate and enjoy! No configuration required.</li>
</ol>

Better Howdy

Remove and restructure the 'Howdy' line by changing 'Howdy' to 'Logged in as'.

shibulijack

If you are looking for a way to change the Howdy text in the admin bar, then you are in the right place.
Change the Howdy text to whatever you wish, right from the admin panel!
Works with WordPress 3.3.1

CJ Change Howdy

A slick WP plugin that lets you change the "Howdy" text.

Better Howdy vs CJ Change Howdy