Just found out this recently, and I am sorry if this is well known for most, but still I think it's worth a remark. Digg has an inbuilt option to automatically submit new diggs by importing your own rss-feed, this is specially useful for those running autoblogs or just regular plain blogs, as there is no need to configure any plugin, because it is all done directly in digg settings. You can access this option in the account\settings\import feeds, then all you need is input your feed, and get it verified. The verifying part can be tricky, as I only managed to get done successfully by adding a test post with the code provided in the title, and deleting after it became verified. It takes a while for it to start "digging" new posts (as in hours), but as soon as it is done it's really autopilot forever, just keep in mind that it will only update new posts, and not your whole blog content. Been using this in one of my autoblogs, don't know if there is any daily limit, as mine only posts 2 new ones a day and having no issues with that .