I suggest looking at the wiki.
But, there are HA control systems that work very well with this system...
The GC-100, from Global Cache' was the first major I/O controlelr to be supported by LinuxMCE. You can use it to control A/V devices, but also relay pads to control things like drape motors, and sensor connectors for door contacts, emitters, etc...
For lighting, ZWave and Insteon work best, although you can use X-10 computer interfaces.
I connect my door contacts, etc normally used for security to the GC-100, so I don't NEED a panel, although, you CAN add a panel if you wish. (I use a Nokia N800 as my orbiter and house controller, which amongst other things, displays the security keypad).
Again, I highly recommend looking at the wiki, because a wide variety of interfaces and systems can be combined together to produce the home control you need.