The Arduino family of boards make great micro controlls for the sensors and actuators commonly found in home automation devices. Nolaria Consulting offers arduino board development and custom software for special purpose devices or prototype development.
The Raspberry Pi board (both the A+ and B+ models) are a significant jump up from the Arduino boards that often run a full Linux (Raspian, etc.) distribution. This allows on-board web servers (Apache HTTPD) to installed for development and experimental purposes. Nolaria Consulting has considerable experience with Linux development and has conducted it's down RPi hardware experiments.
The Open HAB architecture leverages the power of Java to build home automation devices and connect them to a hub and controlling applications. It has full support for iOS and Android applications and is fully supported by a growning community of developers. For DIYers, this is a great way to get into IoT and smart home devices.