The silverlight PivotViewer control allows you to build very large collections and embed them on your website. Works really well for collections that provide a visual representation of the data you are navigating and uses the silverlight deep zoom feature so navigating high resolution images is very quick.
The original Microsoft download is no longer available from the Download Center, but it is preserved in the Microsoft Silverlight PivotViewer archive.
Microsoft Learn also preserves the PivotViewer class documentation.
The Netflix and Hitched demonstration sites originally linked from this post are no longer online in their PivotViewer form.
Scott Guthrie’s archived Silverlight PivotViewer Now Available article provides a more in-depth look at the release.