In Mango we have enabled setting the referer header (and many other headers) on HttpWebRequests. One question that popped up a few times: how do I use this with the Image element and data-binding to download my images. Here is a quick sample to demonstrate how you can do this.
1. Step: define a custom attached property on Image that takes the URI to your image.
2. Step: implement the download piece when the property changes and customize the header as needed.
3. Step: Now use your brand new property in your app's XAML.
Full sample project is attached.