Paul Graham (whom Ben referred to earlier) is in the process of designing a language called Arc. He has put up a page with all the [link|http://www.archub.org/arcsug.txt|suggestions for arc]. One particular set of [link|http://lispmeister.com/cgi-bin/blosxom/lisp-news/moon-on-s-expressions.html?seemore=y|comments from Dave Moon], who helped with Dylan macros, might be what you aiming at. He explains why he doesn't like s-expressions:
I want to comment on your use of S-expressions, based on what I learned in my couple of years researching Lisp hygienic macro ideas and working on Dylan macros. Summary: I learned that S-expressions are a bad idea.
The knock on getting away from the s-expressions has always been that it makes macros difficult, if not possible. Moon seems to believe that if all macros are completed at compile time, macros can be achieved without s-expr:
I think you should limit the language to what you know how to implement, so the macro special-form should only be allowed in places where its complete flow is visible at compile time and should never be allowed to materialize as a run-time object.
Of course, a Lisp diehard would argue that the distinction between compile time and runtime is arbitrary and that there should be not hard lines drawn between the two. Having macros expand during runtime provides some interesting possibilities when it comes to designing systems (especially systems that program other systems).