It didn't start out as an experiment, but I started using SEO techniques for a website before I was able to revamp it. I was just getting it listed in various directories, using low-competition (but important) keyword phrases. It was for a swimming pool installer, so the phrases were Connecticut Pools, Connecticut Swimming Pools, etc. The homepage at the time was a flash animation splash page. Anyways, the website originally didn't rank for any of the phrases with Google, Yahoo, or MSN, but after some work it started ranking well with Goggle and MSN. But not Yahoo. It took a ridiculous amount of time, like 3 months, for us to gain control of the site from the website designer and remove the splash page, so I don't think it was just a timing issue. There was enough time for Yahoo to have ranked the site for at least some of the phrases. Now that I have taken down the splash page the site ranks just as well with Yahoo as it does for the other two. Oh, and Yahoo was indexing all of the pages on the site, and it was ranking the company name in the search results, but not any of the keyword phrases from outside links pointing to the site.
It's amazing when three and a half year old posts get dug up. I guess it shows that some people do use search after all.