AOE Static - Varnish caching for magento
This modules adds advanced varnish functionalitiy to your Magento shop. The module handles the communication between Varnish and Magento, both on filling and on purging the cache. Therefor the modules adds information to the response header.
In addition to that, the module has the functionality to request customer related information such as mini cart and login state via AJAX once the side is loaded. So this module also allows caching of pages when the customer already has some items in the cart.
The easiest way to install the module is with the use of modman. Alternativly you can download the module as archive and copy the folders accordingly. Don't simply copy the folder over your magento installation, the pathes in the module are not the same as in the magento folder. See the modman file to get the relations.
The module adds a new entry into you cache list. Enable the Varnish-Cache there. Also there is a configuration section under Advanced -> System -> Varnish Configuration.