The concept of Pay Per Click is that you get what you pay for. It is one of the centres of huge profitability, and perhaps one reason why organic SEO has been given the run around in the recent past; if you are a search engine that makes huge profits from paid searches, why would you make it easy for people to get it for free.
At OpenG we learned how to manage pay per click campaigns, and believe that they should go hand in hand with any good organic SEO strategy.
One scenario is that in the beginning, when a company is not going to be recognized by the major search engines due to a 'delay effect' of three + months, paid search is the way forward. After this period we can ease off and see how much exposure the website would gain naturally.
The heart of good PPC management is common sense. People who are very good with semantics tend to understand the ins and outs of PPC, because if you choose key phrases that are popular for the wrong reasons, it could end up costing you a lot of money (choose to put some bucks on Paris Hilton right now and you won't get a lot of Hotel enquiries).