I had never heard of GigJam before today, but it immediately impressed me. This Office365 service, which started out as a closed Preview then was opened to everyone on Windows, Mac, and iOS in June of 2016, is now out of its testing phase and finally available on the Play Store.
The idea is simple enough: you want to share a specific document or piece of information with someone to get their opinion, negotiate with them, give them advice, show them how things should be done, etc, but you don't want to share all the document and you don't want it to be available to them past the needed time. What do you do? You can minutely blur out unneeded details and share ephemerally through some messaging app that allows it, but that takes time and looks very unprofessional.
GigJam streamlines the process, letting users temporarily share photos, Word, PowerPoint, and PDF files, or send specific parts of data from Office365, Asana, Saleforce, Trello, etc (without the other person having access to the specific app and platform). No need to manually blur anything, you just cross a paragraph and it's invisible to the recipient. Uncross it and it shows up for them. You can even choose if the other person has read-only or also write access to your shared documents.
The GigJam Android app is available for free on the Play Store, but remember that you'll need an Office365 subscription to benefit from it.