The new Komodo IDE 4.0 is the first unified workspace for end-to-end
development of dynamic web applications. A rich feature set for client-
side Ajax languages such as CSS, HTML, JavaScript and XML, coupled
with advanced support for dynamic languages such as Perl, PHP, Python,
Ruby and Tcl, enables developers to quickly and easily create robust
web apps. Komodo is the first IDE to provide professional debugging
tools for Ruby and Rails application development. The Ruby interactive
shell is available separately or from within debugging sessions.
Komodo is the IDE for Ruby and Ruby on Rails!
http://www.activestate.com/products/komodo_ide/?_x=1