On every single one of your web pages, add links to Del.icio.us, Digg, StumbleUpon, Technorati and Reddit so that users can easily help spread your message and content. This includes landing pages and microsites. By having users backlink your content, you are helping boost your natural search engine optimization.
And, don’t forget your emails. Besides the typical “forward to a friend”, allow users another easy opportunity to share your message by adding these social networking links. You don’t want to overcrowd your emails (and have your main message lost), but it might also be a good idea to provide links to your MySpace, Facebook and LinkedIn accounts.