praeclarum 

SQLite-net is an open source and light weight library providing easy SQLite database storage for .NET, Mono, and Xamarin applications. This version uses SQLitePCL.raw_basic to provide platform independent... More information

NGraphics is a cross platform library for rendering vector graphics on .NET. It provides a unified API for both immediate and retained mode graphics using high quality native renderers.

NView is a cross platform user interface library for Xamarin.iOS, Xamarin.Android, and Xamarin.Mac.

Cross-platform library for rendering vector graphics and writing graphics-rich apps. Supports iOS, OS X, Android, Windows Phone, Windows RT, WPF among a variety of file formats.

NView.Controls contains several controls for the cross platform user interface libary NView.