[puredanger]

I find http://clojure.org/cheatsheet to be a great help in getting an overview of what's in the core library.

[platz]

Yes the cheat sheet is great once you 'have a foot in the door', so to speak.

For beginners, getting familiar with namespaces in the REPL quickly is key, if you're trying to load a sample of code froma file.

Also another gotcha is multiple arity functions which I haven't seen before (in a dynamically typed language).