You can purchase 'ads' related to specific keywords to give you top rankings on Lycos for example. But, my advice would be to steer well clear as they are not blended with the natural results, look horrible and do not offer a good Cost Per Click or ROI over time.
Also, if you do purchase an ad for 'widgets' and someone else gets one for 'blue widgets' you loose all that traffic. Not that they refer refers much traffic anyway... ;-)
I think that if you advertise on Overture, you will start getting calls from these fly by night companies claiming that 35 million people do searches in the address bar and that you are getting the first chance to buy it. In these cases, you can buy the keyword or phrase but the scam is that users have load their browser.
Read through WebmasterWorld and you'll see real quickly what works best for people...OT, Adwords, and optimizing for Google and Inktomi. That's not to say that there are not hundreds of different ways to get traffic, but these seem to be the best for a lot of people.