Tell why you think Python, Perl, Ruby, etc is easiest for plugging in modules from other languages with minimal thought.
To clarify, an example: I want to write business logic in Python, but use functionality that conveniently exists as a Perl module.
In other words, which language "just works" with the most modules?
Perl has very good support for other languages via the Inline set of modules.
Inline::Python allows you to import Python modules, classes and functions into your Perl code and call them from Perl as if they were native - see Importing Functions.
Inline::Ruby works virtually the same way.