When deciding what program to write your R code in it is important to consider a number of factors so you can keep organized and work efficiently.  I found this article useful for getting started.  Text editors include syntax highlighting and other useful features often including text auto-complete functions.  Integrated Development Environments (IDEs) include text editors but are much more powerful.  They include file organization systems, integration among various systems, debugging, and more.  The power does come with the cost of more complexity.  When considering your options, it’s important to also consider what other programming languages you will be using and if you’ll be using different operating systems.  I use a Mac and write primarily in R but sometimes use a PC and am learning more HTML and PHP.  I would also consider using LaTeX in the future.  Therefore, I need a flexible program that works on a variety of platforms.

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.