Google Scholar
While it by no means replaces databases, Scholar is a Google-styled search engine that allows you to search for scholarly articles digitally or in libraries. It should appeal strongly to teens who believe that research begins and ends with Google. My favorite feature is the direct access to articles and / or citations that have cited the article you are reading. The results also provide links to books that are available as PDFs (full or in preview) in Google Books.
Unfortunately, not all of the articles are available directly in full-text - some of the links take you to citations on publishers' Web sites where you can purchase the article; this could be much less of a problem for students searching through universities and research institutions who have access to online subscription versions of the articles. There is also a heavy emphasis on results for articles that have already gathered a number of citations by other scholars, which could skew research.
Like Wikipedia and vanilla Google, Google Scholar can be a valuable springboard to further research, provided users are aware of some of its limitations. Try it out by searching for articles on some esoteric topic - I guarantee you'll have fun!
