Tasky is a simple cross-platform todo/task application sample that allows you to track todo/task items.
Tasky supports iOS and Android - each with a native UI written in C#. It uses a local SQLite database to store the tasks, which are saved and read with SQL.
Common code lives in a Shared Project, which is referenced by each application project. This project type requires Xamarin 3 (Xamarin Studio 5.x) or Visual Studio 2013 Update 2 (which supports the Shared Asset Project project-type). It is compatible with the free Starter Edition of Xamarin.
The equivalent app written with Xamarin.Forms is called Todo.
Bryan Costanich, Craig Dunn