Zen is my favorite theme (hell, I have even learned 80% of my drupal themeing and HTML/CSS best practices in general while using it). And among the many things that makes Zen such a useful theme for me is - its configurability.
A recent client requirement of mine requires that I create a custom Zen theme which has a sort of 'color scheme' that can be quickly edited to drastically change the appearance of the site (in terms of colors).
There are a few ways I could do this, but I would prefer doing it the right/drupalish way, such that others can use such a feature too. You can see some of the possible approaches listed in this comment - http://drupal.org/node/1053734#comment-6582334
Would love to hear from the community on the right way to proceed on this.
Thanks in advance.