xCSS is for PHP, and looks great, but haven't played with it yet...
I love LESS (see
http://lesscss.org/docs.html ), which only works for
Ruby.
Funny thing: LESS does not have inheritance: it supports mixins! This
way you can have a kind of "multiple inheritance" - if you will...
Also, if you're a Rails fan, check out More, a Rails plugin (see
http://github.com/cloudhead/more ).
Check also styled_objects, a Rails plugin (based on LESS) that allows
to do much of what Nicole advocates for -
http://github.com/pgte/styled_objects
.