A little over a year ago, I bought a domain name. I built the skeleton pages, but did not yet have content. A week and a half ago, I was finally able to add content, applying standard on-page optimization. (I could not add content before now, because the related "widgets" did not yet exist, but I knew they would eventually exist when I bought the domain name).
One week ago, I pointed a link to the site from a very related site. This related site, I believe, has a fair amount of trust. Two days after that, I obtained a listing in one directory. This directory is not one of the "biggies", but it is also not a spammy type either.
Today, one week later, here are the results. (I've used SEOmoz's Keyword Difficulty Tool to judge the competitiveness of the phrases).
Competitive Keyword Phrase:
Google - #16
MSN - #3
Yahoo - not in top 200
Mildly Competitive Keyword Phrase:
Google - #1
MSN - #2
Yahoo - not in top 200
Non-Competitive Keyword Phrase:
Google - #1
MSN - #1
Yahoo - #20
The site consists only of 3 pages. Google has indexed all 3. MSN and Yahoo have each indexed 1 (the home page).
Of course, only time will tell how long these rankings last, but it was an interesting experiment nevertheless. Take from it what you will, but I believe the value of just one relevant, trusted link cannot be overlooked.