I completed the first 50 problems at 4clojure.com.
The site helps you learn Clojure in the common way by presenting you with a long set of tasks.
As well as setting the problems it tests your answers live in the browser.
You can follow other users. Once you complete a problem you can see their solutions.
Sometimes that leads you from a solution that looks like this:
fn [coll] ((fn dist [prev coll] (lazy-seq (when-let [[x & xs] (seq coll)] (let [more (dist (conj prev x) xs)] (if (contains? prev x) more (cons x more)))))) #{} coll))
to one that looks like this:
reduce #(if (some #{%2} %) % (conj % %2)) []
Good stuff.