Clojure programming in Emacs is well supported by a combination of the excellent clojure-mode, paredit-mode and CIDER, the Clojure IDE and REPL for Emacs (a great alternative to the now deprecated combination of swank-clojure and SLIME). You'll find detailed instructions on setting them up in clojure-mode's README. Most Starter Kits come bundled with Clojure support.
Use cider-spy to send code snippets and text exchanges to each other etc, as well as EMACS bookmarks.
yasnippet snippets for clojure (in MELPA).
ac-cider is a completion source for Emacs auto-complete package that uses CIDER (and Compliment) as candidates provider.
clj-refactor is a collection of simple clojure refactoring functions. Available in Marmalade and MELPA.
The clojure cheat sheet for emacs packaged into an easy, fast, searchable, offline form.
Typed Clojure mode
The official Typed Clojure Emacs minor mode.