I installed a firefox/chrome extension that is supposed to notify on follows and more, and it has worked a couple of times, but not on other events, so I'm not sure about this, but here is the link:

https://addons.mozilla.org/en-US/firefox/addon/buildteam-notifier/?src=api

Maybe it works better on chrome; I'm using it with firefox. It seems to get it's notifications from an api url:

https://steemit.com/api/v1/notifications/stanleyparker

Do let us know if you find a good notification solution; I can't believe there isn't something better for browser based users :(