A well-documented online platform for enabling machine learning research is one use case that should have obvious interest. I think Tensorflow.js should work pretty well at this point, and I've heard of new-fangled APIs such as WebGPU that could start being put to good use.

One thing that's fascinated me for a while has been the concept of rolling your own hardware that can plug directly into the web. (I know Chrome has had WebUSB and WebBluetooth enabled for some years now.)