First, let's talk generally about approaches to doing research on the Internet. The world wide web has provided the ability to share and find lots of GIS-related data, or at least find where they are stored. But what strategy would you take if you were going to look for GIS-data out on the web? When I ask this question in my face-to-face classes, the typical answer is: "I go to a web search engine, like Google http://www.google.com/, and do a search." And indeed, Google is amazing and certainly works for many of our searching issues. But we sometimes forget that it is only one of many approaches to searching the net. Thanks to the librarians at the University of California at Berkeley, there is an excellent set of web pages that describe a much deeper internet searching strategy. This section will utilize their material.
Keyword searches on search engines : Search engines are web databases that have been built by computer programs called "spiders" that "crawl" the web looking for web pages to inventory. Google has become the most popular of these, although there are others. See http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/SearchEngines.html for a description and comparison of search engines and to learn more about how search engines work.
Note the UC Berkeley librarian's warning: "Google's popularity ranking often makes pages worth looking at rise near the top of search results. Google alone is often not sufficient, however. Less than half the searchable web is fully searchable in Google. Overlap studies show that about half of the pages in any search engine database exist only in that database. Getting a second opinion is therefore often worth your time. For a second opinion, we recommend Teoma, now merged with Ask.com, or Yahoo! Search http://search.yahoo.com/"
Subject Directories : What I find students don't always understand is that there is a distinction between keyword search engines that inventory web pages, and "subject directories" that use humans to organize various pages or sites. For a list of subject directories, see http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/SubjDirectories.html, also graciously provided by the librarians at UC Berkeley.
One handy hint provided by the UCB librarians: Do a search in Google or other search engines above for a topic and add "subject directory" next to it. For example, if you are interested in Forestry, try "Forestry Search Directory" in the Google keyword line. You may find some specialized directories that are maintained that could be quite useful.
Meta Search Engines : These are search engines that build their databases by searching other search engines. See http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/MetaSearch.html for a list. We tend to agree with the Berkeley librarians and don't recommend the use of these systems. In our view they "free ride" on the hard work of the other search engine organizations.
"Deep" or "invisible web" search engines : There is a huge amount of information on the web that are stored in databases attached to the Internet that search engines like Google and others cannot read. Deep web search engines are tools that actually provide information on these deeper databases. These searching facilities are less well known. See http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/InvisibleWeb.html for a list of search engines that do search these deeper Internet resources.
Mechanisms to search listserv or discussion groups : The Internet has a relatively long history of discussion groups, beginning with the "Usenet" groups that started in the early 1980s. The Google search engine provides a mechanism to search these groups. For example, if you are looking for GIS data relevant to Forestry, for example, you might be able to find a discussion group on this topic, or GIS using this search facility. See http://groups.google.com/. If you find a group that is of interest, you could then read their archives, or possibly send an email specifically to that group. But of course, rules of "netiquette" apply http://en.wikipedia.org/wiki/Netiquette.
Try going to http://groups.google.com/ and search for a group of your interest, such as "Forestry". You may discover discussion groups you were not aware of.
Direct e-mail : This is another way of finding information, but is perhaps your last resort. Using this technique you find via search engines people with expertise in what you are looking for, and then email them directly with a question.
Author tracking : Author tracking is a way of using your Internet browser to scroll through an author's web pages. If you find a web page of interest, you simply edit the active URL in the Browser address bar to "go up one level" and see if there are other related pages that aren't specifically linked to the one you are on.
Traditional methods : on-line journals, library indices: Of course, there are a variety of traditional search approaches found at various libraries that shouldn't be forgotten as a resource!
Lastly, the UC Berkeley library folks provide a nice document describing their recommendations for using all of these tools. See http://www.lib.berkeley.edu/TeachingLib/Guides/Internet/Strategies.html for a five-step overview on Internet searching strategies.