We have a demo chat app using NimQML.
However, I think most of us had issues with DOtherside compilation at one point or another. Also it hasn't been tested for a while but we pinned all dependencies via submodules including the Nim compiler so it should be OK.
Now about the app, it's a Nim proof-of-concept of a decentralized chat app based on the Status protocol and can connect to the Status channels. Presentation here: https://discuss.status.im/t/hello-stratus-toying-around-with-nimbus-and-qml/905
Abu idea for a possibile usefull app? Yet another to do list?
I would like to see a c2nim frontend: You have two editors, one for inserting Nim code, the other one read-only showing c2nim's results.
For showcase already commented above.
Obviously in almost 2020, you should tag your demo with either AI or Blockchain.
How about visualizing the training of a neural network? This is a demo that run in the browser but everything visual is Javascript which AFAIK is easy to embed in QML: https://github.com/Vindaar/NeuralNetworkLiveDemo