Top 20 NuGet xamarin Packages

Reactive extensions for MediaManager
A panel that slides out from the bottom or top of the screen
Currently only supported for iOS
An Action/Task Message Pump for running commands on a dedicated Realm thread.
Genesis.Join is a simple library that adds a Join extension method to IEnumerable<string>.
A Xamarin CustomRenderer that render Icon for TabbedPage for iOS & Android, using Icon property on child pages. Use IconTabbedPage class instead of TabbedPage class, and add the name of your static image resource on the "Icon" property of your childs pages, eg. "user_icon.png", and it will be load...
Xamarin bindings for ExoPlayer
This library is translated from BottomBar(https://github.com/roughike/BottomBar) v2.1.1
Gradient.KeyValueStorages package contains interfaces for store your settings in simple structure. Also, with Android and iOS implementations.
Gradient.Timers package contains interfaces for Timers (which can be used in PCL) and their implementations for Xamarin.Android and Xamarin.iOS.
Xamarin Audio Manager provides a simple way to play audio files in Xamarin Forms projects. The Supported Xamarin Platforms are: iOS Android UWP Windows 8.1 Windows Phone 8.1 //Sorta, needs some work but how many people use win phone ;)
Sound manager plugin for Xamarin.Forms.
GameCenter PlugIn for Xamarin.Forms.
Invention for Universal Windows (WinRT).
Implementation of the Technology Solutions barcode reader configuration API for use with Universal Apps, Universal Windows Platform, Xamarin and Xamarin Forms