I'll start by saying I'm self-taught, everything I know I've picked up from programmers in the family, self interest and trial and error.
I'm currently reading Cocoa Programming for Mac OS X from Aaron Hillegass, but I'm unable to stay interested. I think the main reason I'm losing interest is the absence of the main reason I like Javascript and PHP, which is the overall portability that allows development, hosting and testing on any platform (I have Windows 7, Mac OS X and Linux). Coming up with a project - and therefore staying interested in the language - is much easier when I'm able to use it everywhere.
That said, my question is as simple as a request for information on cross platform languages (Java? C++?, * ), or perhaps some suggestions as to projects or methods that may keep me interested in a language long enough to actually be able to start making functional applications.
For clarification I'm looking for overall knowledge of a language rather than a specific API or Toolkit. From there I could learn toolkits, external libraries and other things as I progressed. The main problem right now is finding a language that is cross platform and preferably respected by the Stack Overflow community (hence posting this here, as this has been an extremely valuable tool for me in the past and I enjoy helping others when I can).
I think Ruby is a good idea. It's very different from Java but not soo much that you will not be able to grasp the concepts. Also it is an easy language to learn. Once you learn Ruby, you'll keep thinking of it.