Someone made a comment about word clouds on Facebook yesterday, and
being the smartass that I am I couldn't resist:
perl -e 'while (<>) { $c{$_}++ for (split /\W+/); } print map {$_ ?
"$_ => $c{$_}\n" : ""} (sort { $c{$b} <=> $c{$a} } keys %c)'
Takes text as STDIN, Outputs "word => occurrences", one per line, in
descending occurrences order.