It's a monopoly as far as the 'competition' is unbelievably lame.

The story of overture + yahoo etc is amazing.

What about Quigo? http://www.quigo.com

Being a monopoly isnt illegal. Making an excellent product isnt illegal. The problem is using that monopoly for anticompetitive ends, eg pushing competitors out of other markets (Netscape).

Yes it is. Research Alcoa

I just did & unless I'm missing something, Alcoa was sued for anticompetitive practices.

Do you mean Adsense?

Why can't he find anyone to replace them?

Yahoo and MS won’t give you enough traffic. And I am not saying "they won’t give you same traffic for same money". No, they simply don’t have enough searches, in my experience.