>> Arachno Ruby is quite good also.  It's still a work in progress but I love
>> it's debugger.
> 
>  Another vote for Arachno Ruby (http://www.rubyide.com)
Ditto - as you say - work in progress, but still very usable as is. 
(doesn't help with the GUI part though - it has no GUI tools in it as yet)

Graham