What is the low hanging fruit in driving traffic to a new website?

We are a few weeks away from launching our web app and getting marketing strategy in order.

What are the "low hanging fruit" ways to drive traffic to a new website which isn't known or have any investors.

It's easier for venture backed startups to get a piece written about them on blogs like Techcrunch and VentureBeat. But what can a bunch of unknown founders do to drive traffic?

Getting listed in relevant directories. Betalist, Go2Web20, RepresentPA, there are lots of startup roundups that you can get included in.

Get on twitter now, pre-launch, and start building your audience. Twitter is a great tool to reach out to influencers, participate in hashtag twitter-chats, find people talking about the problem your startup solves and engage them, and promote content you're creating. Spend an hour each day on this -- you'll get better connected to the industry, your following will grow, and you'll see more traffic coming from links you tweet.

Throw a launch party. Invite friends over, invite other startup folks you know over, invite reporters from the local newspapers and relevant bloggers in your area over. Ask people to tweet and share on facebook (or LinkedIn) about your startup.

Ask for feedback / help within startup communities. Hacker News, /r/startups, etc. Great places for a "we just launched, have any feedback or marketing advice for us?" post. You'll not only get some useful feedback, some people may be connected to the industry you're targeting and can help you with some real promotion.

Be active in communities relevant to your target market. This is the big one, and again, one you should start immediately, before launch. Find online communities your target market is active in, and get active in them yourself. Be helpful, add value. And when you launch, if it's the kind of community where advertisement is accepted, go for it. Otherwise, go the content marketing route, add links in your profile, forum signature, etc.