I try not to toot my own horn, but I wrote this little quadtree library that tickles that elegance part of my brain. I try very hard to write elegant code. I have other Clojure repos, but they suck. :P

https://github.com/janetacarr/quadtree-cljc

Anything by James Reeves aka weavejester (https://github.com/weavejester).

Metabase's toucan (https://github.com/metabase/toucan) has some elegantly annotated source code: https://rawgit.com/metabase/toucan/master/docs/uberdoc.html