Open websites, or those freely available on the web using a search engine like Google, are becoming increasingly valuable to researchers as more and more government, educational institutions, and foundations are providing information and data about their work online. While there is A LOT of great information out there, remember that anyone can put information on the open web, so evaluating the material to make sure it is credible becomes more difficult and important.
Many of the best sites to use are those from international (.int), education (.edu), government (.gov), and private organizations & foundations (.org). To easily search for sites from these entities, use the "site:" search to limit your results.
Citing what you find on the open web is difficult--you may be looking at any number material types (books, journal articles, magazine articles, video, etc.) and if that is the case you need to cite it as the specific material type, but indicate that you accessed it through an open website. If the item doesn't seem to be any of the traditional material types, it may just need to be cited as a plain website.