I just rolled this in the last few minutes, because YUI Test has tons of weird overhead, and JSUnit's in-browser runner drives me up the wall.
I'd love to hear it if there's an existing project or methodology in the spirit of KISSUnit! Either way, enjoy the hack, and please rip my style, etc to shreds.
My preferred JS test runner is QUnit from the jQuery project. It's a very similar design to KISSUnit, but not quite a bare-bones simple.