Pushbullet is my favorite custom notification app. I use the Pushbullet app regularly for Android to get notifications when utorrent completes a download. I used IFTTT recipes to monitor reddit to find out when dognzb.cr had open registration so I could get in. I also use it for free game deals. I use it for IFTTT recipes for all kinds of notifications for monitoring RSS feeds and searching reddit for various keywords.
Pushbullet iPhone App Released
Pushbullet can also be used to get notifications when Nzbdrone downloads a TV show and also when Couchpotato downloads a movie on your watchlist. Before now you could only get Pushbullet notifications on Windows and Android. Recently the Pushbullet developers released their official app so you can get notifications on your iOS devices.