Notifications
Pushalot
Website: https://pushalot.com/
PushBullet
Website: https://www.pushbullet.com/
NotifyMyAndroid
Website: http://www.notifymyandroid.com/
Pushover
Website: https://pushover.net/
Growl
Website: http://growl.info/
Prowl
Website: http://www.prowlapp.com/
Media Centers
XBMC
Website: http://xbmc.org/
PlexServer
Website: https://plex.tv/
PlexClient
Website: https://plex.tv/
Others
CustomScript
More information: https://github.com/Sonarr/Sonarr/wiki/Custom-Post-Processing-Scripts