In general I make a resume targeted to the company I'm looking to apply for (or if it's a job site the type of position I'm most interested).
With that in mind I keep the main language that the company cares about front and center, and maybe a few supplemental languages if they are a multi-language shop. For specific positions I do research into what languages that position most requires. For sysadmin for example, I would most likely put Ruby (Chef/Puppet), perl (parsing, general scripting), and bash (general scripting).
If you really want to go into depth, there's always the interview for that.
My main issue is that I want to avoid needing to customize my resume to the company every time. I already spend a bunch of time writing cover letters to companies, and most of the time you never even hear back. (I'm applying to internships)
With that in mind I keep the main language that the company cares about front and center, and maybe a few supplemental languages if they are a multi-language shop. For specific positions I do research into what languages that position most requires. For sysadmin for example, I would most likely put Ruby (Chef/Puppet), perl (parsing, general scripting), and bash (general scripting).
If you really want to go into depth, there's always the interview for that.