I've only used Rails a bit, but I've used Ruby a lot. It's by far the most flexible language I've ever used. It allows programmers to modify the most fundmental aspects of the language. Some argue this is a bad thing, and it may be. However, having the freedom to do that is very empowering. Don't get me wrong, other OO scripting languages are great too... Python for example. And, they share many concepts with Ruby. The things that make Ruby stand out (to me) are the ease of modification and syntax flexibility. IMO, Ruby is a wonderul toolkit that will allow one to build most anything, even more specialized tools like Rails.