I think it all depends on what your project does, for example, is an online service for Yuriko or physicists.
1. sending to all friends and please pass it on
2. if you have something new to write — to write the news and send in the media
3. publishing links in different groups in the VC, etc.
4. Buy, if you have money, the advertising, it is better not banners and links, and even better to pay for the action — registration, downloading, filling out questionnaires, etc.
5. sending email newsletters, not spam, for example there are paid options, advertising the services of the type Spaylog or HotLog. If the service has no such option — invite them to do, you will be the first customers (assuming that the database of contacts of their clients they have )
7. video SEO
8. participation in competitions, rankings
9. contests for attracting attention and audience to play out the new iPhone 4 for those who will lead new friends and Ave.
I do not agree that good service does not need to advertise. All the advertise themselves, but for different and Facebook and Google, and Porsche and Mercedes and Coke.