EmacsFamily editors are probably the reason that Lisp has been such a popular MacroLanguage.
or maybe its the reverse?
Wikipedia: http://en.wikipedia.org/wiki/Emacs_Lisp Manual: http://www.gnu.org/software/emacs/manual/elisp.html
Lisp is well suited to being a MacroLanguage. It is a complete language which is relatively easy for people to integrate or write their own. It supports both procedural and functional styles as well as the ability to define new concepts (via LispMacros?).