World Cat/First Search: A catalogue of books available in libraries worldwide, and especially in North American university libraries.
L'Année Philologique: The standard bibliographic database for research in Classics; contains virtually every publication of interest from the 1940s until recently. The online search engine takes a little getting used to, but once mastered is a very powerful research tool. The help file for L'Année (as Classicists call it) can be found here.
List of Standard Abbreviations Used for Journals in Classics: This web site (from the UC Berkeley library) will "decode" abbreviations used for journal titles by L'Année Philologique and other classics bibliographic databases. Another, shorter, list of the major journals only is here.
TOCS-IN: A huge bibliographic database for articles (but not books) in Classics and related fields, focusing on major journals and other collections since 1992. It is not nearly as complete as L'Année Philologique, but it is very easy to use and often an excellent place to start, especially since it preferentially directs the student to recent publications in major journals.
Gnomon: Another Classics database, which includes a number of works not in L'Année or TOCS-IN. For some reason, the search engine interface has recently become much more awkward, and the English version is no longer available. To use Gnomon, simply type your search terms into the box shown and click "Start."
JSTOR: The major archive of scholarly journals, including many in Classics and history. A JSTOR search will almost certainly turn up articles of relevance to your topic. What makes JSTOR special is that the articles are then immediately available on-line to users form licensed sites (like Skidmore).
Bryn Mawr Classical Review: A very good place to go for reviews of books in Classics and related fields published since 1990. It usually makes sense to skim reviews of books before trying to read them or ordering them on ILL. The link to the searchable archives can be found at the bottom of the homepage or by clicking here.
Perseus: In theory one of the best Classics resources on the web, with online texts, images, dictionaries, etc. Unfortunately, it has been plagued for years by severe server difficulties and is often so slow or unreliable as to be unusable. Still, it may be worth a try.
The Skidmore Guide to Writing: An excellent home-grown resource. If you haven't at least skimmed it, you should.
Writing in Classics: The Skidmore College Classics Department's guide to writing. The pages on research papers are especially relevant to this course.
Haverford College Guide to Citing Sources in the Classics: The use of ancient texts as sources poses special problems in the writing of research papers. This is a brief but handy guide to correct citations. Particularly valuable are the sections on "Using Quotations" (including how to reference information in an ancient work without quoting it directly) and "Citing Ancient Sources."
List of Standard Abbreviations for Ancient Authors and Texts: The Interactive Ancient Mediterranean Project provides a complete set of standard abbreviations for ancient authors and works. An even more comprehensive list can be found in the Oxford Classical Dictionary, pp. xxix-xliv. (The abbreviations now standard are not always the same as those used by Marrou in Education in Antiquity.)