List of home automation systems?
The following protocols are listed in Wikipedia:


C-Bus: @wikipedia
EnOcean: @wikipedia
Insteon: @wikipedia
KNX: @wikipedia
UPB: @wikipedia
X10: @wikipedia
Zigbee: @wikipedia
Z-Wave: @wikipedia


In addition to these, I know there are the following systems:


FS20
HomeEasy
HomeMatic
iComfort
Kopp FreeControl
Belkin WEMO: @wikipedia
Intertechno
ELRO


Actually, I do not know whether some of these systems do not use some protocols above.

There are already some question concerning this topic:


Which communication bus systems for home automation?
What are some scalable, affordable home automation options?
What are the pros and cons of different types of smart switches (that are on the US market) ?