Ask HN: Interesting things to do with old smartphones?

I now have two old Android phones and am looking for ideas of something interesting to do with them. I've had old phones before, but without wifi they've been limited to just games, playing music, or reading ebooks. Now with wifi and some power, there are surely some more interesting things to use them for.

So far the best I've come up with is using them as wireless webcams using IP Webcam. They could also be alarm clocks or be used for streaming music or news. But what else?