VoiceIn - speech recognition
There is a very good extension for Chrome, which allows dictating text to any website (such as webmail). This works nicely with the Chrome Browser but crashes on Vivaldi, apparently because it wants to use the camera instead of the microphone.
This would be a killer extension- as language can be switched quickly and it is very precise using the Google speech recognition (apparently much better than the Microsoft system).
I love Vivaldi - but that feature would be just excellent for me.