You can dynamically compile and run ClojureScript scripts so long as you have properly hooked things up to a JavaScript engine. I've started on an effort that makes this easy OS X, wrapping JavaScriptCore and I could see similar efforts for Node.js. Here's what I've been working on:
http://planck.fikesfarm.com It can run scripts you have on disk, etc, and it has basic file I/O capabilities at the moment so you can write simple text processing scripts, for example.