Elvis is a clone of vi/ex, the standard UNIX editor. Elvis supports nearly all of the vi/ex commands, in both visual mode and ex mode. Elvis adds support for multiple files, multiple windows, a variety of display modes including "hex" and "html", on-line help, WYSIWYG printing, and other miscellaneous extensions.
flex.rb is a regexp matching and scanning library for the Ruby language. It is more than 3 times faster than Ruby regexps, and supports matching text arriving in multiple parts (via async, non-blocking I/O). flex.rb embeds the GNU Flex 2.5.4 (fast lexical analyzer generator) as an engine, and all of Flex's functionality is accessible from Ruby scripts.
ICU provides a Unicode implementation, with functions for formatting numbers, dates, times, and currencies (according to locale conventions, transliteration, and parsing text in those formats). It provides flexible patterns for formatting messages, where the pattern determines the order of the variable parts of the messages, and the format for each of those variables. These patterns can be stored in resource files for translation to different languages. Included are more than 100 codepage converters for interaction with non-unicode systems.
Text::Template is a module for doing dynamic content generation in Perl. You can embed any Perl code into a file, and then make a call to the module to `fill in' the blanks in the file. This is good for generating HTML pages and form letters. It was first released in 1995 and is very stable, very fast, and very reliable. It is also integrated with Perl's Safe module in case you don't trust the template author.