I've been on the hiring side of the interview table for web developer positions a lot in the last few years. While only having professional experience in PHP is

I've been on the hiring side of the interview table for web developer positions a lot in the last few years. While only having professional experience in PHP isn't a big deal, I have to say that folks who've never shown an interest in another language or facet of software development don't tend to impress. PHP is a very pragmatic, simple language with a complex and baroque set of libraries. It's great for hacking together websites, but working with PHP (even for many years) doesn't tend to teach you the kind of technical and aesthetic judgement that differentiates an assembly-line coder from a productive, engaged hacker. Learning Ruby or Python might be the shortest path to another gig, but it probably won't push you outside your comfort zone far enough to really improve your programming if you stick to the usual Rails/Django garden path. If you want to really push yourself and grow as a developer, learn something completely unrelated to the standard LAMP stack. Lisp (especially in a modern form like Clojure) is a good choice, as are Smalltalk and Erlang. C++, Java, or C# may let you jump up a pay grade or two, but tend to lead into dead-end "enterprise" coding, unless you're lucky enough to stumble into a top-notch shop that happens to be using them for their efficiency rather than their "manager-approved" status. Most importantly, I'd suggest actually building something in whatever language(s) you decide to pick up. Reading blog articles and tutorials is all well and good, but it's far more impressive for you to be able to show code and talk from experience about the relative strengths and weaknesses of the languages you've worked with. Even a half-finished side project hosted on GitHub (or hauled into your interview on a personal laptop) will go a lot further than regurgitating buzzwords on demand.