Sorry for not providing links. I may update as time permits.

Ok, for completeness I'm providing them myself. (Part has already been done by naikonta.)

• Perl Idioms Explained by various authors - approach #2:
• Perl Idioms Explained - $|++
• Perl Idioms Explained - keys %{{map{$_=>1}@list}}
• Perl Idioms Explained - ${\$obj->method} and @{[sort @list]}
• Perl Idioms Explained - my $string = do { local $/; <FILEHANDLE> };
• Perl Idioms Explained - @ary = $str =~ m/(stuff)/g
• Perl Idioms Explained - && and || "Short Circuit" operators
• Perl Idioms Explained - my ($foo, $bar) = @{shift(@_)}{qw/ -foo -bar /}
• Perl Idioms Explained - !!expr
• Perl Idioms Explained - my $count = () = /.../g
• The Lighter Side of Perl Culture by eyepopslikeamosquito - approach #2:
• The Lighter Side of Perl Culture (Part I): Introduction
• The Lighter Side of Perl Culture (Part II): JAPH
• The Lighter Side of Perl Culture (Part III): Obfu
• The Lighter Side of Perl Culture (Part IV): Golf
• The Lighter Side of Perl Culture (Part V): Poetry
• The Lighter Side of Perl Culture (Part VI): April Fools
• "Sports Illustrated" by merlyn - approach #1:
• Swimsuits2004
• Swimsuits2005
• Swimsuits2006
• Swimsuits2007

(Could not find anything for "obfu balls".)