Some of the requested features on the digg forums have been taken into consideration and Digg announced the update on it’s Digg Reader platform.
View Unread Only
To browse only your unread items, simply click All Items in the top right corner, then select Unread Only.
Mark As Unread
You can now mark read items as unread by clicking on the button at the bottom of the item or using the keyboard shortcut, m.
Export Your Subscriptions
You can now download your subscriptions as an OPML file. Simply visit the Settings page and click Export.
Check out these new features and more at digg.com/reader.