UNESCO's free online database to translations from 1979 to the present. Contains over 1.3 million records. The database allows you to search for all translations from one language to another (say, everything translated from Slovak into English) by date, or search by author, subject or word from the original title. Covers both translations in books and anthologies as well as in journals published in about a hundred of UNESCO's Member States since 1979.
1932-1986 in print Main Library Z6514.T7 I42 Print version covers years before 1979.
Difficult to use, but helpful to find out if something was ever translated into English, or when it was first translated.
Gale Literature Resource Center
In some cases, particularly in the online version of the Dictionary of Literary Biography included here, there will be information on English language translations.
Literatures of the World in English Translation: A Bibliography.
This is a great resource, but badly needs an update. Only good up through about 1960.
The Oxford Guide to Literature in English Translation.
Edited by Peter France. New York: Oxford U. Press, 2000.
An excellent source for general information on the art and science of literary translation. Also excellent for learning the current state of translation of a country's literature into English; while not comprehensive, it provides an update to the Literature of the World in English Translation series (above). Has a useful index to author's names.
There are many, many bibliographies of specific literatures in translation. To find them, search the following subject headings in the library catalog (replace country as needed):