This section lists version numbers, FTP sites, mailing lists, newsgroups, and other information for many important packages, extensions, and related programs. There is some overlap with the Lisp Code Directory, but these entries give more detailed information.
If you know of any other packages that are so substantial that they deserve to be mentioned here, please tell me. Having its own mailing list or newsgroup or more than half a megabyte of source code are good signs.