Stylus w/nib. SASS (via Ruby or node) w/Compass. LESS. Mimosa won't bother compiling your partials individually, but when your partials change it'll compile whichever files at the root of your CSS tree need compiling.
Plain JS, Plain CSS, no templates? You're a classic and Mimosa's cool with that. Files that don't need compiling will just be copied, but they'll still get the royal treatment, including linting and RequireJS verification.
Mimosa will keep track of your dependency graph and alert you right away if you've mis-typed a path, referred to something that doesn't exist, or have a circular dependency. It will also keep tabs on your shims, maps and plugin paths.
Using an external Mimosa module, you can code using the CommonJS format with your AMD/RequireJS application.