My question is: what are the essential "must know" Clojure libraries and functions to know beyond those covered in the above learning plan?
Looking at Clojure Contrib, there are large number of libraries. As a professional (or OSS) Clojure developer, which do you find yourself using on a daily basis? Which ones are not so useful or otherwise not commonly used (i.e. are esoteric / do not come up often in day-to-day coding).