Josh Betz

A simple plugin that allows blog owners on a multisite network to use a custom favicon by uploading it to the root of their theme directory. Ideal for people who host clients on their own multisite install or want to run multiple domains off of one install.

Network Favicons

Allows blog owners to use a custom favicon just by uploading it to the root of their theme directory.

Nazmul Hossain Nihal

This plugin is for adding favicons to WordPress site.
Using this you can add favicons to :
<ul>
<li>Home Page </li>
<li>Login Screen</li>
<li>Admin Panel</li>
</ul>

WPFavicon

This plugin is for adding favicons to WordPress site.

Network Favicons vs WPFavicon