I have been using the Ruby and Ruby on Rails specific NetBeans 6.0 beta 1 for about 2 hours a day for Rails development. Beta 2 (just released today) has good improvements for code completion, popup documentation, and general RHTML editing. Good stuff!
I have blogged about this before: I am tired of using so many different programming languages (Common Lisp, Java, Ruby, Python, C++, Prolog, etc.) on customer projects. I am starting up a new (non-consulting) business so I am reducing the amount of consulting work I will accept. I would like to just do Ruby and Ruby on Rails development - turning down other work unless it is very interesting.
Algorithm development and solving people's problems - that is the fun stuff, not keeping current with a half dozen programming languages and dozens of frameworks.