Below is some information on programs that I have tried or am trying now. These all support the R programing language.
- JGR - not sure if I like it any better than the native R GUI for Mac
- Komodo Edit - I've had some trouble with this on campus (socket server problem that I don't understand) but it is a fantastic program when it works
- Eclipse and r-script plugin - this program didn't seem very user friendly but I am starting to try it and many people swear by it for a variety of programming purposes.
- Tinn-R (Windows only)
- GNU Emacs - GNU Emacs is an extensible, customizable text editor—and more. Resources can be found here
- Aquamacs Emacs - text editor based on GNU Emacs that works well on in Mac OS X
- Vim - text editor that works on most OS and for many languages including R
I hope that helps some people and I'd love to hear about your experiences, preferences, and recommendations.