A great example of a multi-faceted application for Windows Phone 7.1 Mango that could be used in a marketing campaign or some similar situation is the new Mangolicious app tutorial from MSDN.

The app contains fun facts, recipies, and a silly little asteroids-style shooting game for Mangos.

The tutorial covers LINQ to SQL or Local DB to SQL along with Silverlight/XNA integration, secondary tiles, and deep linking.

Figure 1 Mangolicious Panorama Main Page

Both the menu and the items in the Seasonal Highlights section act as links to navigate to the other pages in the application. The majority of the pages are straightforward Silverlight pages, and one page is dedicated to an integrated XNA game. Here’s a summary of the tasks required to build this application, from start to finish:

1. Create the basic solution in Visual Studio.
2. Independently create the database for the recipe, cocktail and fact data.
3. Update the application to consume the database and expose it for data binding.
4. Create the various UI pages and data bind them.
5. Set up the Secondary Tiles feature to allow the user to pin Recipe items to the phone’s Start page.
6. Incorporate an XNA game into the application.

If you're interested in building something like this, go check out the tutorial via the source link below.  Then check out these links:

• What’s New in the Windows Phone SDK: bit.ly/c2RmNr
• Tiles: bit.ly/oQlu15
• Combining Silverlight and XNA: bit.ly/p4RncQ
• Local Database Overview for Windows Phone: bit.ly/l23UQM
• Mangolicious on Windows Phone Marketplace at bit.ly/nuJcTA (note: Zune software is needed for access).
• The Silverlight for Windows Phone Toolkit (a free download, available at bit.ly/qiHnTT). Which is used in this tutorial

Source: http://msdn.microsoft.com/en-gb/magazine/hh547105.aspx