ActiveShipping is a unified Ruby API (quite useful on Rails) for shipping information from multiple carriers. It calculates shipping, handling, finds the best price from multiple sources, etc. It is primarily focused on rate requests, but may be extended to cover other aspects of shipping as well. Currently, it includes UPS and USPS modules, and modules for Fedex and DHL are coming soon.
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.
Marathon is a GUI test tool that allows you to play and record scripts against a Java Swing UI. It's written in Java, and uses Python and Ruby as its scripting language (the emphasis being on an extremely simple, readable syntax that customers/testers/analysts feel comfortable with). Marathon includes a recorder, editor, player, and debugger to simplify working with test scripts.