Gyre is a curious new Ruby / Rails IDE, developed by Adam Wiggins, that runs within your Web browser. There are obvious downsides, but the upside is consistent behavior cross-platform. Gyre's in a 'pre-pre-pre alpha' state but is downloadable for you to give it a try. If you have a review or comments about it, there's a Google Groups hosted mailing list to post to, or you can leave your comments here at Ruby Inside.