Ask HN: Uses for old touchscreen devices?

We're now a couple of generations into touch enabled devices (largely Android mobiles and tablets, but also iPhone/iPods/iPads, and other less popular OSes). Some studies and analytics show these devices have an average life of ~18-24 months.

At the end of this lifespan, the phones may not run the latest and greatest OS and apps. However, these are perfectly capable, mini-embedded devices, with a built in display, speakers, a battery and an array of sensors.

So here's my question HN: what have you done with your old devices? Are they lying in a drawer? Did you resell them? Are you using it in some other manner? What simple use-cases would you pay for to extend the life of these mini computers?

I'm checking to see if there's interest in certain uses, or set of applications, and hopefully building these.