Various useful PHP modules
Create/send multipart MIME messages. (See inline PHPdoc for usage information.)
Thin wrapper around PDO with convenience methods. (See inline PHPdoc for usage information.)
Bi-directional comparison of multi-dimensional arrays.
Discussed at length in the user contributed notes at http://ca.php.net/manual/en/function.array-diff-assoc.php where a full, strict comparison of entire trees is needed.