What is the minimum budget to promote a site?

There are also a lot of more specialized communities where you can promote an idea for free amongst the appropriate target market by simply joining a particular corner of the blogosphere, joining certain forums, etc. So this idea may still be applicable.

Then again, if you are producing a website targeting automobile tire wholesalers, no amount of free online promotion is likely to have the desired effect.

Ignore standard (and popular) BS of "promotion through blogging and social networks", that's a myth. A successful blog is a business on its own. PR companies have full-time bloggers, Facebook "friends" and even wikipedia editors to spread the word about their clients, and it will cost you serious money: on par with several full-time yearly salaries. And don't expect to become a Facebook after spending that much. Building a brand in consumer-space entertainment business costs millions of dollars (and some luck, still)

That is a bitter truth, assuming you're after building a sustainable business. That doesn't apply to you, however, if all you need is to get a couple thousand "early adopters", living mostly in Bay Area, create some awareness of what you're doing in SV-circles, hopefully reaching an ear of a potential acquirer so you could flip it for a few million, then hire a good SV-connected PR firm: that will cost you $10-20K/month or get admitted to YC and their PR machine will do the trick.

If you're selling things, you might consider an affiliate program. In one of my startups, I had a couple of hundred affiliates signed on before I launched by giving away free copies. It resulted in hundreds of thousands in income the week we launched. Most of the sales came from the top 20 affiliates.

Potential affiliates are not hard to come by and you only pay if they perform. Just pretend you are a customer, search for your product/service in Google and contact everyone who is on the first page as ads or natural search and give them a copy of your product and ask them to promote it if they like it in exchange for a healthy commission. They've got the traffic, and many of them probably don't know how to monetize it.

It also helps to suggest ways for them to promote your product. For instance supplying custom emails for them to send out to their list, promoting it in their blog, adding your product as an up-sell when their customers buy their stuff from them etc.

You can also setup things like cross-promotional auto-responder messages, where you have a message in your auto-responder promoting them, and they do the same for you. No commissions required.

It all depends on what you're doing. If I knew what you were doing, I'd have much better advice.

Despite what at least one person said, article writing is a great way of getting natural traffic and being slowly gaining traction in Google. It just takes time and has to be done right. Don't over post and make sure you post it to your own site and get it indexed by the search engines before syndicating it.

There are other things you can do as well, like buying domain names that have pagerank and putting content on them that references your site. Risky if you ask me. Google will eventually black-list everyone who does that sort of thing.

You really need to work backwards from the value of the customer. If you have something that directly monetises then you can calculate value of a register user and of a visitor. Back out your marketing budget from there.

However I am assuming you have a consumer app where it is very hard to calculate the value of a visitor/user. In that case you are looking at viral, social media, SEO and paid ads. Viral works if your product is intrinsically viral product (send to friend doesn't count). Social media works if have rich content (how to's, great photos, recent news). SEO is what you do if you can't do the first two (I know of one of the world's biggest travel social networks who never paid a penny on SEO). The problem with SEO is it takes a lot of time to build up traffic.

That brings you to paid advertising. I think paid advertising is great for getting everything kick started but the business model for paid ads doesn't stack up for free consumer apps. Hope that helps.

Here are a few examples of companies that didn't follow this path (at first): Google, Apple, Craigslist, Ebay, Yahoo, Microsoft, Facebook, Youtube... I could probably think of more, but you get the jist.

SEO is important to a lot of businesses (especially ecommerce and UGC plays), but not worth early focus for a lot of others.