You definitely should! Learning new languages is probably my favorite thing when it comes to programming and I try to do it every time I go to a Hackathon. I can definitely say that every time I've learned a new language it's taught me some useful ideas or helped me model ideas better in my head. For example, learning Prolog gives me the tools to plan out really complex rule-based systems on paper very quickly (whereas writing Python pseudocode could take twice as long). This also influences the ways that I write code in other languages; for example, learning Ruby made me rethink the way I program in other object-oriented languages like Java. Instead of using a lot of normal design patterns, I try to write more "DSL" style code and use objects to create literate interfaces. Overall, learning new languages is probably one of the best ways to quickly improve your programming skills.