Electric water shutoff valve that can be operated via WiFi and Bluetooth. Ever left your house for a vacation wondering if you have turned off everything in your house. This would be a solution. A main water valve that can be operated from a smartphone app over WiFi. First Steps: see if this exists, adopt a current electric shutoff valve by adding WiFi capabilities. This would also work really great for Gas shutoff valves.
Electrical circuit breakers that can be turned on and off via WiFi and Bluetooth. This is similar to above, but for circuit breakers. If you forgot to turn off your air conditioner, or heat, or anything like that, you can do so via WiFi and a smartphone app. First Steps: research existence of such a circuit breaker. Look at some self resetting circuit breakers, and if they can be modified with electronic triggers. Probably design it as a pod with control wires going to individual breakers to reduce cost.
Bluetooth electricity use monitor. Inexpensive current meters are available, but I haven't seen ones with bluetooth link and ability to dum historical use information into a smartphone app. This would be very useful for experimenting with more efficient electrical appliances, and comparing power usage of different devices over time. First Steps: search for something like this, if none exist, find perhaps one that works with USB and use it to make a prototype.
Easy to setup real time voting system for class discussion. It's been awhile since I have been in a class, but this has always been an issue in the past. A website that would allow a professor to quickly create a multiple choice question or a set of questions, and students would be able to vote in real time on the answers. No login necessary, students can access the right questions by scanning a QR code or typing in a shortcode into the app. First Steps: see if this exists currently, and if not, make a simple web only prototype. If it becomes popular, make apps, and monetize through ads.
Yearbook photo submission app. A social media app that allows students to submit photos they have taken at school events to the yearbook organizers. Basically like instagram, but where you can only post photos if you are part of a school, and only other people in your school can see the photos. The app would upload full size photos without reducing them in size, so they can be use in print later. First Steps: this should already exist, I am guessing, but if not, think of way to monetize it and build a prototype.
Water tank level monitoring device with BLE communication. Ok, this is a very narrow problem that probably only I really care about, but I need a device that can monitor water level in a tank. Ideally the device should be something I can attach with a magnet to the top of the tank, and it would use sound waves to measure distance between itself and the water level, and report historical data over BLE. First Steps: look for a device like this, if none exist try using ultrasonic range finder as a base for a prototype.
App that reads news to you using text-to-speech. This could be useful for when you are driving or running. Just a simple app that can load and read headlines and stories from NY Times, WSJ, Financial Times, etc. Or even from websites like Hacker News. The app should use default system TTS APIs and have voice control features to reread last few seconds, skip stories, etc. First Steps: see if this exists, it really should, and if not, make it.
Movie about a guy who in the future transfers all of his consciousness, memories, and experiences into a robot. As he is staring at his old body, about to unplug life support, the old flesh and blood version of him wakes up, and starts screaming that he doesn't want to die. Is it murder for your clone to kill you? First Steps: write an outline and a treatment for main characters.
Smartphone app that can use AI to identify fruits, vegetables, and other food items, and give you nutritional information for those items. That's just something that came up yesterday while I was shopping, and I thought it would be a useful app. First Steps: see if this exists currently, research how complex the AI would have to be to identify all of the common vegetables, make the app.
A iPhone app that uses the new AR camera APIs to scan your body and identify posture problems. So many people either have bad posture and don't know about it, or think they have bad posture, but are not sure what the specific problem is. First Steps: research the new camera APIs for AR to see how feasible 3D scanning is at this pint.