TaskyPro is a simple cross-platform todo/task application sample that allows you to track todo tasks. It illustrates proper application architecture layering and uses a common code base for the Business Layer, Data Access Layer, and Data Layer layers. It then separates out the User Interface and Application Layer into the appropriate device-applications.
The application runs on iOS, Android, Windows Phone 8, and Windows 8.1 with a set of common classes shared across all three platforms. It uses Shared Asset Projects for the common code that is referenced from all platform-specific projects.
Bryan Costanich, Craig Dunn