Details
Omni Notes already has a good number of users, but it really seems to be one of the best open-source note-taking apps out there for Android platform, so I'm sure that numbers cat easily grow with some promotion and sharing on social networks. It grown really that much when XDA published an article about it, and the app was still on its early stage of development!
Resources
Feel free to use any resource you find here or produce you own screenshots and (mostly, because I'm not really good at that) great videos!
Deadline
No deadline, let's think Agile. This must be done as soon as possible but good jobs need time.
Communication
The easiest way to manage the collaboration's communication is by using Github issues but you can also eventually use the app's associated communities (Google+ or Facebook)
Posted on Utopian.io - Rewarding Open Source Contributors