By far you get the best ROI from a web site.
I know people that make 10s of thousands of dollars on one contract because someone found their site on the web. Sometimes it can take a few weeks to hit the front page and other times it takes months.
Two factors go into this basically, the on page SEO and the off page link strategy.
If you are using flash on your site, it may look pretty but the SEO value sucks. Ever wonder why the ugly sites rank at the top? Because their on page is great and they have a lot of backlinks. Don't just get one type of back link either. Signature is great here but those have been devalued with the last updates and it is only coming from one domain. You need a variety of domains.
maybe the attached image will help.
