http://www.perlmonks.org?node_id=681911
Description: Sometimes things break because code that worked with certain versions of modules does not work with others. This short block just dumps all the modules in use, with their version numbers when a script exits. By doing it in an END block you get a realistic picture of what got loaded and it will still print if your code dies for whatever reason.
END{ 
    no strict; # access $VERSION by symbolic reference
    print map {
        s!/!::!g; 
        s!.pm$!!; 
        sprintf "%-20s %s\n", $_, ${"${_}::VERSION"} 
    } sort keys %INC; 
};