Some of the packages I have found to be really helpful in apps I have been working on.
Vector Icons Customizable Icons for React Native with support for NavBar/TabBar/ToolbarAndroid, image source and full styling.
Bugsnag My favourite tool for recording bugs. Error monitoring and reporting for native exceptions and JS errors in React Native apps
Image Progress Progress indicator for networked images in React Native
htmlview A React Native component which renders HTML content as native views
Snackbar Material-design “Snackbar” component for Android and iOS.
Storage Local storage wrapper for both react-native and browser. Support size controlling, auto expiring, remote data auto syncing and getting batch data in one query.
React Navigation Navigation for React Native done right.