Because the internet changes every day, it's impossible to keep up with it. Often, the best way to begin looking for something on the internet is to launch a search. For example, practically every university and federal government agency has a web site, and more are adding to the web every day. Here are a few popular ones. Try the internet before you pay for Directory Assistance.
Switchboard is a national phone directory of individuals and businesses.
Certainly not complete, but voluminous. A listing of every university home page, from which you can find phone numbers, faculty profiles or whatever information a university has decided to post on the web. Links to international universities, too. For example, AAAS's EurkAlert service has embargoed material, a phone directory of public information officers and other useful information in addition to releases and journal information. Send a message to profnet and hundreds of public information officers around the nation get your query and have an opportunity to respond.