Ruby, the language, is almost as flexible and dynamic as Smalltalk. It's just that it didn't come with an integrated graphical environment like Smalltalk.

For a glimpse of "what is possible", take a look at TkInspect (1), a set of gems that I'm working on that provide some of the goodies of that GUI, like an interactive, graphical console, a live inspector, a class browser or turtle graphics.

At the moment it's not more than a toy, but it does definitely show what can be done.

(1) https://github.com/josepegea/tk_inspect