I am always open to try new productivity tools — not so many of them are as efficient as they claim. So far, the best productivity app for me is Todoist. It has a clean design, very fast and simple, and can satisfy both adepts of kanban and tasks lists.
Another great tool to work with large chunks of data and in projects is Tadabase.io. You can use it in simple ways to manage your projects, or even to create a public database and charge for access to it.
IMAGING, VIDEO & AUDIO
To download videos from YouTube or just the sound from them, I use Sconverter.
I found a great iOS app to record regular voice calls - Call Recorder Pro. To record a call, you need to merge it with another call to the app’s number that will be recording your conversation. It turned out to be a very simple and seamless action to do, unlike I thought initially.