Aside from TV and gaming consoles, I have yet to see many suggested appliances for Second Screen Apps. I believe that the potential is huge and I decided I'd share some of my ideas.

So what is Second Screen Apps anyways?

In a way, Second Screen Apps are similar to the web interfaces that we have in headless appliances such as wireless routers. You control the device by loading up an interface in your smartphone (or tablet or computer...)
The difference is that your main device already has a screen.

What you can do obviously differs, but there's many advantages to being able to shift the control to your smartphone. For one thing, its precise touchscreen trumps most other input devices you meet in your everyday life. You also don't have to stand in line to get access to a machine. But there's also models where the First Screen helps your smartphone - mainly with having a much larger display surface for the content. I could keep listing reasons but I feel like it's much more real with some examples.

Here are three of my ideas to tickle your imagination:

ATM: While you're standing in line, why not already use your smartphone to choose the amount you'd like to withdraw and whether you'd like a reciept?
Might not save you a lot of time, but if many people do it then the line will be faster.

Interactive mall map: in many malls there's a big touchscreen display acting as an interactive map of the mall to help visitors find their way around. When you've found out where to go, save the map and the coords to your smartphone. Or if there is a queue to the map screen, open the app directly in your phone.

Train station: If you're awaiting a friend's arrival, go to the time table screen and subscribe to delays and the arrival of their train.

Some more ideas in my previous post My side project queue.