The Weird and Wonderful Characters of Clojure by James Hughes.
From the post:
A reference collection of characters used in Clojure that are difficult to “google”. Descriptions sourced from various blogs, StackOverflow, Learning Clojure and the official Clojure docs – sources attributed where necessary. Use CTRL-F “Character: …” to search or type the symbols into the box below. Sections not in any particular order but related items are grouped for ease. If I’m wrong or missing anything worthy of inclusion tweet me @kouphax or mail me at james@yobriefca.se.
Definitely a candidate for your browser toolbar!
I first saw this in a tweet by Daniel Higginbotham.