Configuring editors to display the code nicely is always good.

Emacs

In the git version c contains a julia-mode path-to-julia/contrib/julia-mode.el.(Note: that may change, please in that case update) Adding the following to ~/.emacs should work:

(add-to-list 'load-path "path-to-julia/contrib/") ;Tell emacs to look for the file there.
(require 'julia-mode)                             ;Tell it to load it.
(setq auto-mode-alist                             ;Tell it to go to julia-mode when a Julia file(.j) is spotted.
      (append '(("\\.j$" . julia-mode)) auto-mode-alist))

Maybe you do not want to add the folder, alternatively omit the first line and

cd where-you-keep-your-elisp-files
ln -s path-to-julia/contrib/julia-mode.el julia-mode.el

Vim

Instructions for installing Vim support for Julia can be found in the julia-vim repo, which provides pathogen, vbundle, and manual installation options.

TextMate

Copy (or symlink) the TextMate Julia bundle into the TextMate application support directory:

cp -r JULIA_PATH/contrib/Julia.tmbundle ~/Library/Application\ Support/TextMate/Bundles/

where JULIA_PATH is the location of the top-level julia directory. Now select from the menu in TextMate Bundles > Bundle Editor > Reload Bundles. Julia should appear as a file type and be automatically detected for files with the .j extension.

Other editors

If you figured out how to do it for other editors, dont hold back!