I recently had to solve the 'randomly select n unique elements from an array' problem. The solution I hit upon was to shuffle the list and take the first n elements. The trick being, you don't have to shuffle the whole list, you just need to ensure the first n elements were shuffled:

my @list = 'a'..'z';                                # use your data in
+stead of this
my $n = 5;                                          # how many do you 
+need?

foreach my $i (0..$n-1) {
  my $j = rand @list;
  ($list[$i], $list[$j]) = ($list[$j], $list[$i]);  # swap ith and jth
+ elements
};

print join(', ', @list[0..$n-1]), "\n";
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As you say though, the original poster didn't specify whether unique selections were a requirement.