Flay analyzes code for structural similarities. Differences in literal values, variable, class, method names, whitespace, programming style, braces vs do/end, etc are all ignored.
Flog reports the most tortured code in an easy to read pain report. The higher the score, the more pain the code is in.
Code smell detector for Ruby
A Ruby code quality reporter
A SkunkScore Calculator for Ruby Code -- Find the most complicated code without test coverage!