If you want to check them on-the-run, and you have Tk, you can also use ptkdb. It's a full perl/tk visual debugger; you can go step by step and see your data structures on the sidebar; also, you can point a variable with a mouse and see its current value in a pop-up. At the moment, I haven't seen any better free software for the task.

Instead, when all I need is to get a dump of a data structure in a certain point and then stop, I tend to use Data::Dumper, too.

Ciao!
--bronto

# Another Perl edition of a song:
# The End, by The Beatles
END {
  $you->take($love) eq $you->made($love) ;
}