I saw this question today in one of the forums: how to market a new business without spending thousands.
If it's just money you're talking about then there are quite a few ways, but none of them are truly free. You will always have to invest time and effort.
I'm going to restrict this to marketing online. So let's look at a few ways:
1. Forum Marketing
Do a web search for forums relating to the business you're promoting, find ones that are well moderated and active, and join them. Create a catchy tag line, along with a link to your site, and place it in your signature file.
Be sure to make valuable posts on the forum to demonstrate your expertise and create authority. Don't Spam the forum or you'll quickly be canned.
2. Article Marketing
Write articles of between 500 and 1500 words on subjects related to your business and submit them to article directories like EzineArticles and GoArticles.
In your Author's Bio box (sometimes called a resource box) offer access to more information on the subject you've written about, with a link to your site.
Be careful not to do any direct promotion of your product in the article itself - it will be rejected if you do!
3. Write a Blog
Set up a blog on the site you're promoting and post informative articles on a regular basis.
Many people say you should post each day, and that's good if you can. But if you're struggling for material you're better off going for quality rather than quantity. Quality, valuable articles will work, value-free ones won't.
4. Social Network Marketing
Find social network sites that relate to the business you're promoting. Join the relevant ones, fill out your profile in detail in each and include a link to your site.
Participate in the discussions, being sure to add value. As you do this people will check out your profile and click through to your site from there.
Don't promote your business in the discussions - you will quickly be canned if you do.
5. Search Engine Marketing
If you're building your own websites be sure to set them up properly. Fill out your META data tags for each page individually.
Generate a sitemap and submit it to Google. Remember that each time you add or remove pages from your site you'll need to regenerate the sitemap, upload it again and re-submit it to Google.
Keep your site focused on its subject and find a way to update it regularly (setting up a news page with a relevant RSS feed is one way of doing this).
Set up a blog on your site - this is a good way of getting lots of incoming links, which are important in the eyes of the search engines.
The one point that runs through all of these methods is this: don't directly promote your site (other than through your signature, resource box or profile) at any time.
Just focus on adding value.
Don't approach this with a 'selling' mindset. Rather, approach it with a mindset that asks how you can contribute to the discussions. A 'giving' mindset.
By doing that you'll create credibility and authority. And that's what will lead people to click through to your site.
But a heads-up: this approach takes time. If you want instant traffic then you will need to pay for it, through PPC or other paid marketing channels.