Made by Marc Silverman. https://github.com/silverma/ToggleProxiesPlugin
A plugin for Adium 1.5 that makes it easy to turn all account proxies on or off with a key stroke.
In order to build you'll need to build adium and add the frameworks to the project as detailed here:
http://trac.adium.im/wiki/CreatingPlugins
You can download the built plugin here: https://github.com/silverma/ToggleProxiesPlugin/downloads
Once installed, the Toggle Proxies menu will show up near the bottom of the file menu.