Social Bookmarking sites like Digg, Reddit, etc. all of them you can submit your site or articles in your site via link to and then many people can see these newslines and go to your site. Its worth doing if you can make it become popular.
By bookmarking your site you'r building it link juice. By doing that you'r increasing your site's ranking and PR. This is considered promoting.
The exact same way everyone else does. Bookmark pages with different accounts. It's not magic, it's work. It's a lot easier to pay someone with a good rep to do this for you.