* Setting a timer or an alarm

* Asking for the weather

* Play some (desired) music

Are there other things that these devices ("smart speakers") are really useful for?

A voice activated browser or computer, on the other hand, is extremely useful for those who don't know to type or to use a browser (or a computer). It could be people who are not privileged enough to learn or people who find these very difficult to learn or even small kids. These systems allow the user to accomplish what they want (like searching or opening a website or a game, for example).