On Kooday and recently on Kule Search you can purchase a keyword and link your site to it. Almost everybody loves it because they earn money as long as it lasts.

Even before I knew that there are well known internet crooks behind it, i figured out that it simply can not work on long term. The reason is simple.
There are very few rules. I can buy a keyword "dogfood" and link a site to it that sells furniture.
It is the common users that  make the success of any search engine. Now Kooday launched for the public and people get irrelevant search results so they will go back to old trusted Google again.
Apart from that, the prices of purchasing a keyword is artificially driven up by the owners of the keywords. This is simply not workable. Companies do not want to have check daily if they still own their keyword or have to purchase the same keyword over and over again.
Sure, people are making money right now, some even a lot. But what will happen if Kooday crashes? When it becomes general knowledge it is a scam? Would you join another program from the person who recommended this program to you?
I am the owner of a site where you can buy a keyword an link your site or program to it for 1 year or 3 years (top spot). Nobody can take the keyword away from you by placing a higher bid. You can ad a description and an image to it.
My site is called "Link your keyword", The site is not only visited by online marketeers but also by the general public and is therefore ideal for promoting a niche product or service. We have also 2 special pages: A TE Special where you can promote your TE or promote te-related services and a Tools and E-book special.
When people hover your keyword they see the image and the description. All keyword purchases are manually reviewed by me. Keywords that are reserved and don't match the content are refused.
So go ahead and link your keyword today and get targeted visitors.
Another alternative is K.A.R.T. contextual advertising where advertisers can buy traffic for popular keywords as a low as 3 cents which is far more cost-effective than Google Adsense. K.A.R.T. is part of the Kooiii network which has a social site and a search engine which is rapidly growing in popularity because of the accurate search results ans because it is very user friendly. Of course K.A.R.T. ads are shown in the search engine and on many other sites and blogs because people can join as a publisher and earn money.
More information on my K.A.R.T. Agent site.