So I have an rails admin system that will allow a user to choose a theme, basically a set of SASS color variables that will recompile application.css.scss with the new colors. H
I believe that you could use erb to inline variables in sass. I'm not positive, but I think it would look something like this:
themes/_whatever_theme.sass.erb
$theme_sprite_path: '<%= Theme.sprite_path %>';
$main_color: <%= Theme.main_color %>;
$secondary_color: <%= Theme.secondary_color %>;
These should be created dynamically for each page load. I'm not sure how the caching would work here.