net/http, net/imap, net/pop, net/smtp, net/telnet, open-uri, openssl Base64, Digest (HMAC, SHA256, and SHA384) optparse (option parsing, see the Trollop library for an alternative) Pathname, FileUtils Logger CSV REXML (pure Ruby XML library, Nokogiri is a good alternative) YAML (popular serialization alternative to XML, JSON) Thread (see also Fiber in Ruby core) Timeout ... For a complete list, see: http://www.ruby-doc.org/stdlib Tuesday, September 6, 11