Some questions are easier to answer through the web than others. If it has to do with current events, law, computers, popular culture, commercial products, organizations, or public affairs, the web offers a lot; if you're looking for scientific research or scholarly articles, you aren't as likely to find what you want (though in some fields that is changing). Fortunately, there are ways to mine the Web for the good stuff.
Because there is such a wide variety of information from so many sources on the Web, it's extremely important to evaluate what you find using the same criteria you use for all your sources.
Ironically, Web sources that seem scholarly are quite often badly out of date. The Catholic Encyclopedia, for example, is a copy of a reference work published in 1917. The library has a 2002 edition in the reference collection. The one that is free online is so old it's no longer under copyright, so it's only useful if you want information about the Catholic church in 1917. A few things have changed since then.
The first question to ask is:should I use the Web for this project or not? The Web is great for some topics, but is not a good place to find literary criticism, scholarly analysis of social issues, or the kind of broad overview written by a noted scholar that a really good specialized encyclopedia can provide. In addition to its print resources, libraries often pay for resources that are accessed through the web; these aren't indexed in search engines. Some "free" sites for magazines and newspapers charge for using their archives; library databases offer them at no charge. Consider these steps as you plan a search:
Use these strategies as you sort through your results:
photo courtesy of stuck in customs
There are lots! But these are a few examples of good and useful sites.
Google News - an automated news aggregator.
Images you can use
Flickr Creative Commons - millions of searchable, copyrighted photos that can be reused under stated conditions.
Google Images - to find images you can use without copyright conflicts, search, then click on Search Tools > Usage Rights.
MorgueFile - a collection of free images for creative use.
World Images Kiosk - over 50,000 fine art images available for educational use from the California State University system.
Increasingly, search engines customize results to reflect your individual search patterns. Eli Pariser has some interesting things to say about that.
In addition to limiting a search by date, use these tricks.