Mostly vim, emacs and sublime (there's plugins for all of those). The folks at forio have also started an IDE for Julia, but last I looked they didn't have much

Mostly vim, emacs and sublime (there's plugins for all of those). The folks at forio have also started an IDE for Julia, but last I looked they didn't have much more than an editor (and their website hasn't been updated in a couple months, so I'm not sure what the status is).