My first project was the remote controlled car. It was quite simple to be honest, the guidelines were available on the Internet and it was just a matter of fitting them into the materials which I had at my disposal.
Since then I have done a couple of home automation projects for fun. My house's windows are all opened and closed through our phones. We can set our airconditioning, lights and alarm through the phones too. These didn't really have instructions online, but it's not too difficult to figure out. If you decide to use an Arduino or RPi board to do home automation work I can give you a hand
BTW I didn't set up our automated air conditioning, that was done by a company here. I got interested in projects like that afterward and did the windows etc. HVAC automation is probably the most difficult off the top of my head.
I used a Raspberry Pi and Arduino. RPi was the processor, Arduino was the interface.
At uni, I've created the AI for an intelligent quadcopter. This was done in collaboration with 3 other guys, to be honest, I only did the implementation of their work. I can show you guys some of our simulations that we ran on matlab.