I recently just starting using Devel::Peek to look at my data structures. I love it. After reading the module doco you get an idea of the output from Devel::Peek and the structure of what you are seeing. It shows a wealth of data about your objects, hashes, variables, their types, reference counts, length, size, addresses and so on. It will even show what class your objects are blessed into. Very cool!

Note: It will only show the first 4 elements of a structure unless you specify for it to show more by sending it an additional integer. eg. Devel::Peek::dump(\%hash, 8)

For example this is 4 element dump of my %hash:

SV = RV(0x1a7ba4c) at 0x1bd1e98   <<--## a scalar that is a ref
  REFCNT = 1               <<--##  Its ref count
  FLAGS = (TEMP,ROK)
  RV = 0x1b5e014           <<--##  The ref value
  SV = PVHV(0x1b25384) at 0x1b5e014  <<--## the scalar ref points to a
+ hash
    REFCNT = 2             <<--## The hashes ref count
    FLAGS = (PADBUSY,PADMY,SHAREKEYS)
    IV = 1
    NV = 0
    ARRAY = 0x1a49e84  (0:7, 1:1)
    hash quality = 100.0%
    KEYS = 1
    FILL = 1
    MAX = 7
    RITER = -1
    EITER = 0x0
    Elt ".*" HASH = 0xaeb62926         <<--## First element of hash
    SV = RV(0x1a7ba3c) at 0x1bd1e8c    <<--## is a scalar ref
      REFCNT = 1
      FLAGS = (ROK)
      RV = 0x1bce2c4
      SV = PVAV(0x1bcb7c4) at 0x1bce2c4 <<--## which points to an arra
+y with 5 references
        REFCNT = 5
        FLAGS = ()
        IV = 0
        NV = 0
        ARRAY = 0x1a49634
        FILL = 1
        MAX = 1
        ARYLEN = 0x0
        FLAGS = (REAL)
        Elt No. 0               <<--## Element zero of that array
        SV = PV(0x1b3dbf0) at 0x1bd8098
          REFCNT = 1
          FLAGS = (POK,pPOK)
          PV = 0x1a4980c "return_me"\0   <<--## its value
          CUR = 9
          LEN = 10
        Elt No. 1                      <<--## ... and so on
        SV = PV(0x1a6097c) at 0x1bd80b0
          REFCNT = 1
          FLAGS = (POK,pPOK)
          PV = 0x1a49834 "fullfile"\0
          CUR = 8
[download]

Anyway, it blows my hair back :-)