Much of the information that is stored is 'public information', meaning that anyone has may access it. Most of the time the trick is knowing 1) who has the information and 2) how to ask them for it. (In most cases, if you ask, you will receive, except for that information which is protected, as it should be, by privacy laws.)
Investigators - Investigators are filed under the heading of 'records' because the function of an investigator is to investigate - find information. They have taken the time (that the rest of us don't have or don't want to invest) to learn where to go and how to get the information others want. The section on 'Investigators and Investigative Services' includes a multitude of associations for investigators as well as interesting facets like forensics and crime scene reconstruction.
Libraries - Through this portal can be found every major (and most minor) libraries in every major language - from the Library of Congress to the public libraries of the Baltic States. Today's Internet places the world of information at our fingertips. This section of Advanced Search opens the doors to every door to every library from Milan to Bejiing!
Newspapers - Newspapers contain a wealth of information. They are one of the largest stores of historical information. Many newspapers today may be accessed online, including archival copies. Search here for any newspaper, anywhere in the world - many interpreted in popular languages.