FormValidator is a Ruby port of Perl's Data::FormValidator library. It makes it easy to validate data coming in from HTML forms by providing a robust set of methods to handle required fields, dependent fields, filtering, constraints, tainting, and defaults. Its modular design allows you to easily add your own filters and constraints and also lets you to keep validation data outside of your CGI scripts.
MP3OCD is an MP3 categorization program written in pure Python. It differs from traditional MP3 categorization because it queries freedb.org to obtain information about a set of MP3s and automatically renames them to their appropriate names. It also sets up a set of symlinks to make burning easy.
Daemonize is a Ruby module derived from Perl's Proc:: Daemon module. It allows you to easily modify any existing Ruby program to run as a daemon. Converting a program to a daemon by hand is a relatively simple process; however, this module will save you the effort of repeatedly looking up the procedure, and it will also ensure that your programs are daemonized in the safest and most correct fashion possible.