Developing a Windows Phone Application from Start to Finish
This article, which includes an accompanying sample application, will guide you through every step of building a complete Windows Phone application. It will take you from defining your application, to adding images, to working with data, all the way to publishing your application on the Windows Phone Marketplace. Along the way, you will learn the basics of Silverlight and Windows Phone development as you create a simple fuel-tracking application.

Windows Phone - Silverlight & Media
Want to add media to your Windows Phone application? This article covers the various ways you can integrate media into your app. You will delve into support for media formats on Windows Phone and learn how to easily play media files using the included Silverlight controls. In addition, the article demonstrates how to consume video sources from third-party websites, such as YouTube, and how you can let users play that media right from within your application.

Windows Phone Data
In this article you will learn everything you need to know to incorporate advanced data capabilities into your Windows Phone application. Learn how to access, store, display, and work with data in your app. The article even helps you with data binding to build advanced user interfaces with minimal coding.

Beginning 2D Game Development
Learn how to write a 2D game for the Windows Phone platform. This article provides step-by-step guidance for creating your own space shooter (called Mars Invasion), leveraging the XNA Game Studio 4.0 gaming libraries typically used to write games for the PC and Xbox 360 platforms. Along the way, you learn about the main game loop, creating the graphics, state machines, and collision detection.

Building 3D Games for Windows Phone
This article demonstrates how to write a 3-D game for Windows Phone. As a sample project, it guides you through creating a three-dimensional maze game where the player explores a maze looking for treasures and overcoming obstacles to reach a final goal. The article explains how to create objects in three-dimensional space and how to transform those objects. It also provides an overview of how culling lets XNA Game Studio draw closed solids more efficiently.