If I was forced to program in another language, the Perl language feature I would miss most would be:

• formats
• heredocs
• do blocks
• block eval
• array slices
• qw operator
• next and last
• trailing commas
• statement modifiers
• variable interpolation
• anonymous subroutines

Note, I'm not talking about CPAN, the testing infrastructure or anything "big". I'm interesting in what makes Perl so nice to use when you're working at the coalface.

(the list is sorted by length of item, at least in my font).