One such proposal that I like is "sweet-expressions" at http://www.dwheeler.com/readable/. That page also has a rudimentary set of implementations for some Lisp dialects, including Scheme. It's too bad that new Lisp dialects never seem to take notice of these features.

Also, quick links for others looking for Pliant:

Pliant syntax docs: http://hc.fullpliant.org/doc/language/syntax

Pliant language docs: http://hc.fullpliant.org/doc/