Miguel,

I'm a little frustrated by the dynamic typing of Ruby as well, but you get
used to it quickly. You might rather be interested in the scala language
(http://www.scala-lang.org/) which keeps many of the useful constructs of
ruby, but uses an even stronger typing system than java does. I'm still new
to it, but I'm not sure it has many of the neat introspection properties of
ruby that let you twist and bend the language. 

Also check out the Eclipse ruby plugin, which I just discovered and which
makes the lack of typing easier to work with...