Sites such as Digg, Reddit, Stumbleupon and Facebook are swarming with like minded people who just want to surf the net and find great deals or great stories. So what your job would be is to get the message right infront of there eyes in a professional and kind manner, so it grabs there attention. There are various ways to perform this, but one thing you have to remember is that you must get it correct the first time. Especially if you are promoting a brand, because if someone lays there eyes on a promotional piece that is not even worth a penny then they will ignore every future effort. Great First Impressions are a must.
I believe that social media optimisation has the ability to strongly get your name out there especially if done correctly. Getting onto the front page of a major social site will of course bring you a heap of traffic, but it's the actual after wave that is the most interesting. You will get people actually saying did you read that story about etc etc, and they will of course link to your site, also helping with your SEO efforts. A major story would probably have a ripple effect lasting for atleast two months.
The other major benefits you will notice from social media is how low costing it is. Most of the social sites are free to post to, you just have to have some techniques and know how then you are on your way. Not only will it help with getting the word out, but as I mentioned before it will be a great addition to your SEO efforts, getting natural backlinks the ones that search engines all love.
Looking to the future I do believe that any sort of internet marketing is the way forwards. Gone are the days of advertising on TV and newspapers, why because it's just so expensive and you can reach a more targeted audience online. Why promote a website to people that are sitting infront of the TV or looking at the newspaper? Why not grab them when they are actually on the internet and can view your site in a second. With sites like YouTube and Google news we no longer need the traditional advertising methods.