Marketing is the key of any startup. All of us have great products, but how to market our product is the most crucial. Twitter wasn't the first microblogging, Facebook wasn't the first social network, About.me wasn't the first profile site, Foursquare started 1 month later than Gowalla, etc.
Please share with us, marketing strategies that you have tried that worked, and not worked. We may have heard a lot about inbound marketing (blogs, tweets, social media...) or outbound marketing (press advertising, tv, radio, billboard...), but how do people exactly do it to go viral?