While we're on the Clojure topic, what's the preferred quick-start guide to learn the language and tool-chain?

I like Clojure for the Brave and True [1], although it can be a little goofy at times.

Leiningen [2] is the standard build tool, and Clojars is the standard package repository [3].

For web development, Ring [4] is the standard HTTP solution, while Compojure [5] is generally used for routing.

http://www.clojure-toolbox.com is good for everything else.

[1]: http://www.braveclojure.com

[2]: http://leiningen.org

[3]: https://clojars.org

[4]: https://github.com/ring-clojure/ring

[5]: https://github.com/weavejester/compojure

It's also worth mentioning Pedestal[1] - in place of Ring and Compojure. Pedestal is set of libraries for building web services that is fast and secure by default. It fully embraces async capabilities (unlike Ring which is inherently synchronous), and maintains most Ring compatibility. It sits upon battled-tested technologies (Jetty, Tomcat, JBoss, Undertow, etc).

[1] https://github.com/pedestal/pedestal