Catalog of Free Compilers and Interpreters http://free-compilers.sharnoff.org
This directory, aimed at developers (rather than researchers), provides links to compilers, compiler generators, interpreters, translators, important libraries, assemblers etc.
Compilers.net http://www.compilers.net/
This site started in 1997 as a student project. Since then, it has become an important source for information on compilers and programming languages. They are constantly adding new topics, including compiler links and tutorials,full text books and chapters, tutorials, information on individuals and companies involved in compilers development.
Free Compilers and Interpreters for Programming Languages
http://www.thefreecountry.com/compilers/index.shtml
This site almost disappeared when the administrator, Christopher Heng, could no longer maintain it (due to costs and time involved in maintenance), but his "fans" inundated him with e-mails begging him to continue with offers of free hosting on their servers. So he took up one of the offers and the site has been resurrected with a new look. This example indicates how sites develop and then disappear, but also shows the power of the medium to bring parties together. It is indeed an excellent site linking not only to free compilers and interpreters but also to the whole gamut of programming tools -a site to bookmark certainly. The site has free programming resources, webmasters' resources, security resources and utilities.