Josh Maxwell

The <a href="http://ardentpixels.com/" rel="nofollow ugc">Ardent Pixels’</a> Gravatar plugin adds the gravatar photo associated with the user’s email to their profile page. If they do not have a gravatar account, it displays a link to create one. And is MultiSite compatable!
This plugin does not add gravatar support to your theme.
<h3>Notes</h3>
= Donations = 
Feel free to <a href="http://ardentpixels.com/josh/contact/" rel="nofollow ugc">donate</a> if you liked this plugin.

AP Gravatars

A simple plugin that adds the gravatar photo associated with the user's email to their profile page... MultiSite compatable!

Tom Lynch

Switch Theme allows WordPress Network Administrators to switch all the themes on their WordPress installation to a different theme in only a few clicks.
This is particularly useful if you have large network of blogs which you wish to switch to a new version of your theme.
If you find this plugin useful please <a href="http://supportus.cancerresearchuk.org/donate/" rel="nofollow ugc">donate to Cancer Research UK</a>, and let me know what think you via <a href="http://tomlynch.co.uk" rel="nofollow ugc">my website</a>.
Switch Theme is only for use with WordPress installations with multisite enabled, it will not work on standalone installations or WordPress MU.

Switch Theme

Switch Theme allows WordPress Network Administrators to automatically switch all the themes on their WordPress installation to a different theme.

AP Gravatars vs Switch Theme