The emacs starter kit I mentioned can be found at
https://github.com/technomancy/emacs-starter-kit and has some setup
instructions. It requires emacs 24. With it you can get clojure-mode
clojure-test-mode, paredit and other niceties. If you install
leiningen and do a `lein plugin swank-clojure 1.4.0` then in emacs M-x
clojure-jack-in will start and connect a nice repl.
It looks like the 1.4.0 release of swank-clojure has finished
integrating swank-cdt, so now it has a debugging environment. You can
read more about that at http://georgejahad.com/clojure/swank-cdt.html
starting at the "Test Drive" heading. I've played with it a little
bit, and it seems it nice. Stack traces get indented better and
colorized as well.