Best of all is "stop when this exception is thrown". I use that to start 90% of my investigations.
This post is enough for me to decide to get this NOW.
If you're interested in the debugger, I spoke about it at Clojure/West this year: https://www.youtube.com/watch?v=ql77RwhcCK0. It shows how the debugger works and I talk about the problems debugging Clojure code, of which there are many.