ion.pe
Powerful programmer's editor with integrated REBOL/Core interpreter. First editor with such integration. Description, documents, screenshots, time-limit download.
url: www.techscribe.com/
jEdit-cmd
Run REBOL scripts from within jEdit.
url: www.errru.net/rebol/utilities/jEdit-cmd/
Kate syntax
Syntax highlighting for Kate, a programmer's editor for KDE/Linux.
url: www.errru.net/rebol/utilities/katesyntax/
PayLoad
A freeware encapsulator for Rebol/Core and Rebol/View.
url: rwst.no-ip.com/payload/
REBOL and Emacs
This article covers a variety of ways to use Emacs as a REBOL IDE of sorts.
url: www.frozen-north-linuxonline.com/Howto/REBOL+Emacs...
REBOL mode for Emacs
Correct indentation and styling for REBOL coding in Emacs
url: www.rebol.com/tools/rebol.el
Rebol Unit
A unit testing framework for REBOL.
url: www.vydra.net/rebol-unit/rebol-unit.html
reboLDAP
A project intended to develop REBOL tools for the Lightweight Directory Access Protocol.
url: vvn.net/reboldap/
STEEL
An Integrated development environment for REBOL.
url: www.rebol.it/~steel/
VIM Syntax Files
Syntax highlighting in the VIM editor for REBOL source.
url: www.eandem.co.uk/mrw/vim/syntax/