Here are some links of interest (in alphabetical order):

American Comparative Literature Association - A U.S. based organization for scholars of comparative literature.
http://www.acla.org/

International Association for Philosophy and Literature - An association for scholars concerned with philosophical, historical, critical, and theoretical issues.
http://www.sunysb.edu/iapl/

International Comparative Literature Association - This association supports international research in comparative literature.
http://www.byu.edu/~icla

Directory of Author Societies - This directory provides links to numerous author societies.
http://dir.yahoo.com/Arts/Humanities/Literature/Authors/AuthorSocieties/

Modern Language Association of America - An organization dedicated to both the study and teaching of language and literature. It has over 30,000 members in more than 100 countries.
http://www.mla.org/

The Nobel Foundation's E-Museum - This site contains biographical and other information about Nobel-prize winning authors.
http://www.nobel.se/literature/index.html

TESOL - A US-based professional organization for Teachers of English to Speakers of Other Languages. It has affiliates all over the world.
http://www.tesol.org/