The New York Times has a good article about searching the internet today. It points out some often overlooked techniques as well as ways that tools like Google can be used to provide better results.
It also alludes to special purpose databases and the time and expense that is associated with them. It doesn't get so deep as to mention services like West Law for doing for legal research. The article also didn't address that there are many ways of finding information on the internet. Often things that can't be found in Google, for example, might be revealed by directories like Yahoo or DMoz. In addition there are many free databases of information that are not completely searchable by google. Things like property records and marriage licenses are often in these databases.
On the same day the Times has a really saddening article about the state of people helping people. The premise of the article, supported by a handful of people they talked to is that technical people (geeks) are tiring of helping friends and family solve computer problems. Several of the people they talked to go beyond not wanting to help and are hostile towards technical neophytes. Read more about Searching