Maybe this would be too esoteric or somewhat "ahead of its time", but a little more exposure for the unicode tricks that are now possible with Perl RE's could yield some useful surprises for the average reader.
For example, making up expressions and character classes with things like \p{Punctuation} or \p{CurrencySymbol} (or their short forms \p{P}, \p{Sc}) -- and having these work regardless of what language the text is in -- has a certain attraction to it. (Or maybe I just don't realize what a nerd I am to think so.)