@edit: After reading Your answers and some info on the internet I'm confused about two languages. Those are C++ and Python. Python can be used for web so it combine great with my current knowledge. But how about Python for desktop applications? Is it hard to build cross-platform apps? Could You compare for me this two languages?
PS. I'm really glad about all of Your answers. It is very helpful for me & it forces me to productive thinking about my future ;)