Well, I just fell in love with Ruby, when I began to learn it a week ago... I've been programming for 15 years and had been seriously hoping to make my own language one of these days, because all the languages I was used to had severe limitations at every turn. I don't know how to explain all the reasons why I hate conventional languages, but let it suffice to say that Ruby lets you do virtually anything you want to do; it supports a wide variety of programming styles, and can do many things that are difficult or impossible in other languages, such as metaprogramming (the possibilities with this seem endless), arbitrarily changing existing classes (including built-in classes), coroutines (although you'll have to implement them yourself, since Ruby only has continuations built in), lightweight (non-OS) threads, closures, multiple inheritance (well, not exactly, but Ruby's "mixins" are just as good), "freezing" objects, and on and on.
Also, after reading through the online book Programming Ruby, I got the feeling that the designer and developer ("Matz") really knew what he was doing. The parts of the language fit together well and on the whole, the language is well rounded, with a feature for everyone.
Finally, Ruby is easy to play with, because
(1) you don't have do define a class and a method and write a ton of import/include/using statements (as in Java/C#/C++) -- code at the top level automatically runs (in a hidden method called "main", I think.)
(2) you get the interactive interpreter called IRB, with which you can type statements and get immediate results. Multi-line statements (such as method and class definitions) are also allowed.
The one big problem with Ruby is that it is dynamically typed and interpreted, and thus very slow, although I've heard it is not much slower than Python or Perl.
My second favorite language is C# 2.0, which has most of the features I would want in a statically-typed language. (although there's certainly enough missing that I still wish I had time to develop my own language.)