The webhook system of WooCommerce, which is present since a few versions ago, got a good web interface to manage creation and interaction with hooks. For whom do not know what webhooks mean, we can summarize like:
It is a mechanism that you can monitor notification of systems, by using an API, usually allowing to register an URL which runs a program to interpret the received notifications.
With this system, it is possible to monitor events ocurred on WooCommerce. For example, we can monitor new orders and send alerts for sales team to get in touch (it was only a simple example, there is many actions available to monitor).
You can check the full documentation here: http://docs.woothemes.com/document/webhooks/.