Impossible, right? Not really worth the time, right? Wrong on both accounts.
Many times while entering phrases into Google, I find a lot of somewhat related sites, but hardly ever anything exact. So why bother on getting these supposedly un-searched terms?
Because there is a perception that having your site in the #1 spot in Google means that your site is an authority on that particular subject. As any experienced user knows, this is most often not the case, but perception is reality.
Granted, some of the phrases that you can get ranked on may not be very popular, but you never know what a user is going to enter into the search box, or do we ever know at what point of information gathering they are at.
One of the most common traits of searching is that when a user firsts begins a search, they use a broad term, but as they get further along into their search, the phrases become more precise as they themselves filter out the un-related sites.
This is the same concept of which a successful PPC campaign can be run. While it may be great to get tons of traffic for the keyword "shoes", if a user is really looking for "Nike running shoes", the site has wasted money on that search.
Another curious stat that web analytics reveal is that a consumer that comes to a site through PPC is not a life-time customer. They are usually interested in the quick fix, or easy solution. Compared to a user who arrives through organic search engine optimization, they are more likely to be lifetime consumers since they tend to trust a company that has "earned" it's way to the top of the rankings.
By the time a user has a four to five keyword phrase entered in for their search query, chances are that they have already eliminated the "noise" and are focused on the "signal" i.e. the product or service that your site is offering.
One final item to remember is that if you have an exact phrase that is not common to a search engine query, once it gets indexed, it will most like appear in the number one position since the search engines always try to find an exact match when other factors aren't available.
As an example, here are some articles I've written that have a #1 ranking in Google (as of March 14, 2007):
The SEO Halo Effect
All Links Matter
The Benefits of Black Hat Techniques
It's All About Me Advertising
Clinically Proven SEO
Why You Need Outbound Links
-To your online success!