The Netiom (a commercial product) is used by many xAP home automation systems as it provides a ready means of getting inputs and outputs from and to the real world.
Examples of using the Netiom include lightswitches, doorbells, central heating control, alarm systems, pretty much anything where you need to turn off and on something.
The Netiom uses the xAP BSC Schema which is well supported by a number of applications most importantly those that perform the role of a BSC mapper such as xAP Floorplan. This allows one input to control one (or more) outputs or perform some other action.
The other thing about the Netiom is that it is Ethernet connected and therefore can be remote from the main PC. See an example at  where the Netiom controls relays which switch lights and also actuators for controlling radiators.
The manufacturer's website is here