I have been a cyber citizen now for many years. I was lucky enough to be part of internet revolution from quite early days as far as UK goes. I have a lot of experience of using internet as a 'surfer'.What amazes me is growth of market relating to provision of search engines services. I remember when Yahoo! was just about only search. These where days of unbiased search results. The search engine market is now big business, and payment to be listed in one way or another is common.
Google, although apparently providing unbiased results, allows PPC or Pay Per Click advertising by its AD Words campaign. When searching on Google you may notice small advertisement boxes on right of returned results. These are free to display but incur a cost to website owner/advertiser when clicked. Hence pay per click!
Other search engines like Yahoo provide a pay to be included service. Where you may not actually be paying to be listed in search engine results you will be manually approved (or not!) to be included in there yahoo directory for a fee.
But things look like they are due to change. With income now viable for search engine providers, other big players are on horizon all wanting a slice of cake. MSN has recently stopped using other search engines results on its pages and has replaced them with its own search engine.