Here is the most common used Nuget that I had use in the project.
(1) Badge Plugin for Xamarin & Windows
https://www.nuget.org/packages/Xam.Plugin.Badge/
Source Code :
CrossBadge.Current.SetBadge(10,"PetsFrenz");
(2) Circle Image Control Plugin for Xamarin.Forms
https://www.nuget.org/packages/Xam.Plugins.Forms.ImageCircle
Source Code and Details:
https://github.com/jamesmontemagno/ImageCirclePlugin
(3) Connectivity Plugin
https://components.xamarin.com/view/connectivityplugin
Source Code and Details:
https://github.com/jamesmontemagno/ConnectivityPlugin
Other than Plugin , I also suggest to view some resources that help me in development:
(1)https://github.com/liwich/Carpool
(2) https://github.com/mjtpena/Xamarin-Training