Coco is a code coverage utility for Ruby. It can be used from RSpec or unit/test with a simple "require 'coco'". It works with standalone Ruby or with Rails. It displays the names of files that are uncovered on the console, builds a simple HTML report, and reports sources that have no tests. It is UTF-8 compliant, configurable via a simple YAML file, and has colorized console output.
AffirmIt! is a supportive testing framework for Ruby. It tolerates all code, whether it exhibits behavioral challenges or not. It never uses the words "test" or "failure", which would imply a value judgment, or "assertions," which would imply an absolute truth. Instead, it treads softly around code and espouses preferences.
Ackr is a very small subset of grep/ack/rak, for lazy developers. grep is a great tool, a very powerful tool, but often too powerful for simple needs. Ackr looks for a search string in all text files and in all subfolders from the working directory, is case insensitive, has no options, doesn't look into hidden folders/files, and displays the search term in a bold font.