Very high rank for "Freelance Graphic Design" at bonfx.com

I just learned something interesting today. My main domain, bonfx.com, is listed in Google around 50 or so for "freelance graphic design" and "freelance graphic designer" and very highly in a few others. What's interesting is that I have never done anything whatsoever to accomplish this. The site for the last 4 years was 4 pages with very little copy, but it did have the term "freelance graphic designer" on the top of each page. 

So, as I go collecting info about SEO lately, and pondering this fact of where I'm listed through no intentional effort of mine, I discover page rank. I installed the Google Toolbar and went to bonfx.com and discovered it is a 4. I think that's pretty high for a static website, no blog, very little if any content. But, again, the key words are on top. My recent site redesign was SEO friendly, but still no optimized towards the keyword in question.

Well, the answer seems to be that the domain is 8yrs and 3mths old at this writing, and for that whole time, has been a "freelance graphic design" site.

My guess is that if I make any effort whatsoever to "rank up" on these terms, I could get in the top 10, maybe 20. I could probably easily run a blog for freelancers off of bonfx, of which their are many, but leap towards the head of the pack in short order...

Thoughts - anyone?