HANS is a Hardware Actions and Notifications System that allows your plugable hardware to express itself. It's also a reimplementation of the old Hermes project.
In the past, there were no app o system that were supposed to notify to the user when a new device was being plugged. Neither there was any way the user could choose a action for a non-standard device (CD, DVD, usb-stick and so), such to install a specific software to use it, to launch a specific application, load a kernel module, etc. That's is why Guadalinex project decide (back in the 2005) to create Hermes a hardware notification system that let the user to choose come actions and decide what to do with some gadgets that weren't supported upstream.