Also, by putting legitimately valuable content "out there" you are, in effect, doing what people call "content marketing". You want to draw eyeballs to your site/blog/whatever when people search for keywords related to what you are doing.
See, among other resources:
http://en.wikipedia.org/wiki/Permission_marketing
http://en.wikipedia.org/wiki/Content_marketing
Does something like that exist?
1. Post to Hacker News at a strategic time. Be receptive to all feedback and respond to any legitimate concerns.
2. Contact tech reporters and news sources: TechCrunch, Mashable, TheNextWeb, etc. Politely but assertively give them a reason to write about your new product/service. Try to rehearse this pitch a lot.
3. Offer a free demo to influential people. See: tech reporters, startup founders relevant to your industry, etc.
4. Network with favors, not by being annoying. This is hopefully done prior to launch, but in any case the basic gist is that you should aim for quality networking, not quantity. Stay in touch with influential people and help them. They'll help you in the future.
Marketing:
1. If you have money, go for a tightly moderated and exclusive marketing campaign like those offered by The Deck and similar services. These usually cater to the sort of audience you want and are much more successful for positive reception.
2. Make a diverse marketing portfolio networked through other startups that need advertising revenue and through circuits that will likely hit the eyes of influential investors and VC's.
Of course, that's very general. Good luck!
Only if there is something likely to be relevant to HN'ers. A link to the landing page of "Facebook for Hedgehog Owners" is just spam. A link to a blog post about the struggles of founding "Facebook for Hedgehog Owners," is relevant.
That's not to say that links to landing pages are never relevant - e.g. the landing page for a Github project or the landing page of a programming tool are more likely to be directly relevant to HN's audience.
The general rule applies. If the content is good, and there's some luck, it will get noticed. If it's basically a press release, then HN probably will ignore it.