kilinrax: nice code, but we can get rid of your foreach loop: 
open DAT, "ads.dat" or die "Error: cannot open data file: $!\n";

@imgdata=<DAT>;
@imgs = grep { s/^[^|]+\|([^|]+)\|[^|]+\|(?:internal|partner)$/$1/ } @
+imgdata;

$img  = $imgs[int(rand($#imgs+1))];
print "Location: $img\n\n";

[download]

Cheers,
Ovid

I noticed everyone else had better, shorter answers than mine, sniff, sniff, so I just HAD to do something. Here's the regex broken out, for those who have asked for it: 

s/^            # Beginning of string
   [^|]+       # Everything up to the next bar
   \|          # The bar
   (           # Capture to $1
     [^|]+     # Everything up to the next bar
   )           # End capture
   \|          # The bar
   [^|]+       # Everything up to the next bar
   \|          # The bar
   (?:         # Non-capturing parens
     internal  # the string "internal"
     |         # or
     partner   # the string "partner"
   )$          # End of string
   /$1/x       # Substitute $1 for string

[download]
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In reply to (Ovid) RE2): Printing Random Image in HTML by Ovid
in thread Printing Random Image in HTML by damian

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