Here's a general example. Say you need to find out if certain hardware supports linux. Usually your search involves specific hardware models and "linux" and usually there is a lot of cruft in the results (aka ads and vendors (big brother I know you are reading this, please put that in Froogle where it belongs)).

Later on I noticed that my vanity search was listing my blog in the top 5 results on google (referrer logs help here). That was pretty interesting and I'm not saying that I'm one of the most important 5 Matt Harrisons, but for some reason I was up there. Then about two months ago, I disappeared again. (I wish I would have paid more attention, so I knew what triggered it.) No, I was still in the index this time, but pushed off into the nether world of ~150 (ie I might as well not be in the index). Why did this happen? I don't know.
Now to end my rant. Call me a complainer, call me vain, but explain to me why my vanity search brings up the Spike Asset Manager (which I wrote, yet has NO mention of me on the page!) as number two! I asked a professional SEO and he can't tell me either. For what it's worth both yahoo and msn list me in the top 10. Maybe I should switch search engines.
Hey there... I'm not a regular blog surfer, but I have been gathering data
on Page Rank, and your
blog came up.