Doing a macro system for perl could be rather interesting, as its syntax is significantly more complex than lisp's syntax. I can think of a couple of things, though:
Have an inline tag to inline subs. Not, mind, that this will necessarily buy much, as perl's tough to optimize.
Curried functions. No, wait, we're getting those already
Substitutions at the token/AST level. This is trickier, but the regex engine in Perl 6 should be up to it.