The Value of Trust in Social Networks:

On any social network trust can be leveraged for profit. Sounds obvious, but when you think of playing many networks as a game of margins sometimes that means working on zero or small margins until you create a profile you can leverage.

eBay:
A friend of mine buys and sells stuff on eBay, keeping the stuff he really likes, and selling back the stuff that was not as good as he would have desired. The stuff he did not like frequently sells for more than he paid for it because he posts in a clear and honest manner and leverages his reputation.

Some people go one step further and also drive traffic to third party networks for monetization. Others start opening bidding price at way more than an item is worth just to use eBay for cheap exposure to targeted traffic streams.

Other Auction Sites:
As you go on the smaller networks you go into an area of greater risk, since a seller being blackballed from a small auction site would not hurt them as much as a blackball from eBay would.

Sometimes the variety of networks create arbitrage opportunities. In the past I bought some groups of a half dozen or so exceptionally old cheap baseball cards for a few dollars and then pieced them out and resold them on eBay for a decent profit. It was not uncommon for people to pay $10 to $15 for an individual card that was part of a $2 to $4 group.

Amazon:
Amazon has a ratings and review system, just like eBay. Sometimes people will not be interested in buying from you unless you have a profile built up.

As a writer you can make a number of book sales by making sure you review every competing book on the market. After you review enough other books people will trust you more when you review friends books in exchange for friends reviewing your books.

Some people also mention their books in so you want to... lists, even if their book is not on Amazon.com. Originally unknowingly to me, someone else did this for me, and I know it caused at least one ebook sale.

Wikipedia & Spam:
Recently I created a meta search engine and mentioned it on WikiPedia. Was my mention WikiSpam? Maybe, maybe not.

If I had a long established profile with tons of submissions I am sure it would not have been considered WikiSpam. As it sits now, in spite of coverage from SEW, someone at Wikipedia thinks Myriad Search does not have any notability.

Eventually I bet some SEO companies will heavily focus on creative ways of using the Wikipedia for SEO. There may eventually be a company that exclusively works on editing the WikiPedia.

If you can't fit direct links to your site into the guide some people will go so far as to build indirect linkage data, working in articles from well known media sources. For example, I probably could not add a link to SEO Book to the WikiPedia, but I could create a linkable thesis that made linkage more likely, or link from the Wikipedia into an article from the WSJ about an SEO company suing me on some Wikipedia page covering blogging & free speech.

Websites:
Search engines trust sites more as they age. They also trust sites with more quality link popularity as it ages. That sounds like it makes sense without saying, but if you fail to give people things to talk about then slowly you will lose market share to people who do.

Off the start even if you are doing a good job few people are going to see it. As your site exists longer there are going to be more and more ways for people to randomly stumble upon your website.

Personal Branding:
A few years ago would there have been anyone interested or any reason for Andrew Johnson to interview me? Would there have been any reason for others to mention that interview? No way. In the same way algorithms learn to trust you so do people.

After people become exceptionally notable some people will even link in to their reviews of other products (or others reviewing your product).

I Was Here First, etc:
In the Navy one of the guys who was a couple years ahead of me hated me because I did not give him the respect he felt he deserved (just for coming a couple years before me). Sure enough, in spite of him trying to hold me back, I still qualified faster than anyone in my division.

Some people who are more successful are there only because they came first. If you can think of different & better ways to build trust you can quickly pass them up. Look how quickly Threadwatch has taken off. I think many of the other blogs are better because Nick's raises the bar.

Niche:
It is not to say that anyone could walk in and just become synonymous with search the way Danny Sullivan is or Google is, but within every market there are niches that are going to be much easier to do well in.