Ruby on Rails IDE

Because of how Ruby on Rails works (dynamic programming, scripts are run in command line interface), it's really not advised to go for a full fledged IDE when starting out. At this point, you're better off learning the file locations, how files interact, and the rake commands the "hard way".

Any text editor with syntax highlighting and indention support would do. I personally use vim for development (in Linux running in a VirtualBox instance, Rails on Windows is :( ); it might look outdated, but it has a bunch of features not found in typical text editors and is more than enough for coding.

If you're using a mac, TextMate is the way to go.

If you're on a Mac, go buy TextMate. You can easily recoup the small investment with its rich set of editing features and extendability via bundles.

If you're on Windows or Linux, go for Aptana RadRails. IMHO, it's the most functional Ruby on Rails IDE, and can be extended via Eclipse plugins. It can be installed as an Eclipse plugin itself, so if you're using another Eclipse IDE like let's say Flex Builder, it'll integrate well with your current setup and projects.

I'd agree with Datenshi here that Ruby/Rails on Windows is kind of awkward, since most of the tools that a Ruby/Rails developer use can be natively found on Linux (and on the Mac, for that matter).

jEdit! It's a cross platform java IDE that has support for Ruby and a host of other programming languages. There's a particular post somewhere on the internet on how to turn a vanilla jEdit into a full-featured rails IDE by installing several plugins. Also, it can be made to look like Textmate :D

I started with RadRails back in 2007. It was nice. I think it's a very good idea for beginners because of the help options.

But personally want to keep documentation and tools separate. For docs, you can always refer to google or some PDF or the official RoR docs.

GMate (gEdit for Ubuntu) and Textmate (Mac OS) are not IDE's but I highly recommend these two. For GMate, it's really nice ... It seems to be more advanced than Textmate primarily because it is open source. It seems to have better support for some languages. But since I am using Mac for now, I am just using Textmate.

Both Gmate and textmate have autocomplete features. "defcreate" + TAB key for instance.

Go with plain text editors that others have mentioned like Textmate, Emacs, vim, gEdit.

What I like especially about Emacs and Textmate are their ability to "open" a directory. Just go to the directory, then type "mate ." and and Textmate will open a project that corresponds to that directory.

This is very useful when you're studying gems, which is a very common activity in the Ruby world.

For me, I use NetBeans. Aptana is good too, but I have this convenient feeling working with Netbeans (not to mention the Intellisense and autocomplete). And its all in one so you don't need to use a lot of IDE's for diff. programming languages. It also support Haml and SASS so it's really great for devloping rails app. :)

I'd have to agree with Fred. I've been using Netbeans for RoR development for over a year now and some of its capabilities like going to a declaration via command click have been a major help. On the downside, some of its autocomplete functions are too cumbersome (you can always disable them though).

I like the look of Textmate however so I have a theme that reproduces the color and font scheme :D.

Play around with the suggestions you've accumulated in this question and use the one that fits with your style best. And don't forget to read up on the shortcuts and other implicit capabilities whatever IDE you decide on has.

The best IDE is the one that fits your personality. I tried Aptana, emacs, and a number of editors. In the end, I am the happiest with vim.

Well a lot of people would not recommend TextMate if you are asking for an IDE. Coz technically, TextMate is still a text editor. The choice of IDE would likely be determined by the OS that you will use for your development environment.