I don't normally use them so I don't know their rules. These are my question. How many friends can you add on Digg in a day? And which other social media network allows you to add your friends and send them the pages or sites you like i.e. the way Digg is?
Other better social media networks are Mixx, Reddit and StumbleUpon or you may try the latest hype which is twitter. If you reach over 10,000 followers.. Success is in the air, you just need to grab it.
Twittering is already sending me some traffic. If you are using wordpress, there's plugin that makes your every post a twit.