good blog you need to find ways to attract readers (please tell your friends). If you want to have a good presence on Twitter you need followers. If you want to connect through Facebook you need to have friends. At some level there is self promotion throughout the process. You gain readers, follower or friends so that you can tell them about what you're doing.
Working online is also a bit like rolling dice. You know what you hope will happen, but you can't accurately predict with will actually happen. My all-time most popular blog post is entitled Jack of All Trades, Master of None. I think it's a good post, but I've felt much more proud of other posts. I've worked harder to drive traffic to my site by mentioning popular search terms (iPad, Android, PowerPoint) only to find that isn't very successful. The one that hits the top results is the iPad and it's a distant fourth place. Sometimes success in online media is a bit like rolling the dice. You just get lucky.
But in order to get lucky you need to be in place to reap the benefits. My one blog post wouldn't have near the impact if there were no other blog posts. Google wouldn't carry my results very high if I hadn't been blogging consistently for over a year. Twitter followers won't appear if you aren't producing good content. Facebook friends won't materialize if you don't sign up for an account.
How do you use online media for self promotion? How has it worked for you?