How to spread the word about your business fast?

Hi Henrik, there are heaps of free methods for SEO traffic, but may take a few days.
The fiverr website someone mentioned is really awesome and some people also offer to do backlinks which is a must for your site to get in the top search engine rankings too.
Depending on how much time you want to give, you could start a blog, then you can promote that on fb and twitter and search for other people on twitter who also mention something related to your product/keyword you choose.
Submitting articles with your website link in them can be a huge help, writing a really good article(s) will help get higher rankings, with more views which will equal more traffic and its quality traffic as they read your article so they are interested. You can even do a google search on how to write good articles or you can pay someone to do them for you.
If you do a blog, you can submit this to blog directories and help to get even more traffic to your new site. Or you can just submit articles to the blog websites, if you do a google search you should be able to find quite a few blog sites to submit articles, and the same with article directories.
There are also forums dedicated to traffic and websites which can help you too.
It may take a few days, but its all worth it in the end.
Lots of luck!