TextMate (Mac OS X Only)
There is a Groovy plug-in for the popular TextMate editor on Mac OS X here
XCode (Mac OS X only)
A new-format language "mode" for SubEthaEdit 2.x is available here.
Syntax highlighting for Vim was created by Alessio Pace. It is included with the current Vim download, or is available here.
If Groovy is in your path, to run a script from Vim:
or, if you are passing arguments:
:!groovy % arg1 arg2
TODO: Implement complete support for the Groovy language, as has been done for ruby: http://wiki.rubygarden.org/Ruby/page/show/VimRubySupport
Guillaume Laforge wrote a syntax file for the TextPad text editor which can be downloaded
here. This file should be installed in the Samples subdirectory of your TextPad installation.
Jeremy Rayner has written a groovy-mode for emacs, details of which can be found on the Emacs Plugin page.
Russel Winder has started an alternative to Jeremy's based on CC Mode (Jeremy's was reworking of ruby-mode). Also Stuart Clayman has created a Groovy execution mode. See the Emacs Plugin page for details.
Find more info on the UltraEdit Plugin page.