Block This - An ad blocker that works for both apps and web browsing..... And it's FREE.
Package Disabler Pro - A great way to disable the bloat and preinstalled apps that are annoying.
FoxFi - Wireless tether that works. The Pro version doesn't have any caps or limits so it's worth it if you use it often.
What say you?
EDIT: Here are some of the apps that have been mentioned in the thread....
Light flow - allows you to take control of the notifications on your device.
Smart Pocket - Skip tracks with double click volume button and more.
Greenify - "Greenify help you identify and put the misbehaving apps into hibernation when you are not using them."
No Root Tethering "No root tethering. (This works on the Sprint version, and should work on the Verizon one. Not sure about others.) You'll need to get your MSL from Sprint."
MacroDroid Set up macros to perform tasks. I personally use this one to start Pandora when my phone connects via Bluetooth to my car stereo. Works well.
Galaxy Button Lights - Disable capacitive button backlights.
NetGuard - Ad blocking from XDA
All in one gestures - Control your device with simple gestures.
Screen Lock Pro - Allows you to screen off and lock the device. Will not trigger the pin input when you have fingerprint lock on.
OGYouTube - Ad Free YouTube!!
EasyDownloader for Instagram - Save pictures and videos directly from Instagram app (photos and videos).
KLWP Live Wallpaper Maker - "You'll be designing your phone exactly how you want in no time.. And it will keep you busy for sure. The possibilities are endless. It does require Nova Launcher or many others.."
Social Contact Photo Sync - Synchronize your phone contacts with high resolution photos from social networks and partly even from social apps.
Be sure to give a thanks to all of those who have contributed this thread. I will add more as they come in.