Possibilities are endless!
I'm looking forward to getting all my lights on the system. Most lights will be operated by smart light switches (as we have lots of ceiling lights in the house per room, would cost a fortune to replace them all with Hue lamps!)
Bedroom, Living room, Dining room lamps will all have hues eventually to help set the mood. I've some LED strip lamps and curtain LED lamps which I'll connect to a smart switch and I have control of everything just from voice, set the mood, etc!
Heating will be added eventually.
I'm really interested in trying to manufacture something that is capable of driving a simple roller blind. I could easily use a Siemens logo PLC or something like that as the controller. Then work out how to get alexa to tell it what to do (could wire in smart switches to the inputs I suppose...?)