I am stuck in a MySQL/Apache/PHP/JavaScript world.
Is it possible to stay inside that stack yet incorporate other languages and technologies to advantage and increase interest?
The idea is to still serve pages with PHP, but they might have been made with another technology or the JavaScript might have been built with a tool rather than by hand.
Well, the best way to get out of that particular bowl, in my experience, is to dream up a small project that you're interested in and implement it from the ground up with a totally new technology. Unfortunately, most employers won't pay for that kind of thing; even though it makes you a better developer, and improves the bottom line by broadening your knowledge, it's not usually the kind of thing that a manager can itemize and allocate money for. This means you'll have to do it on your own time.
If you can carve out time, I would highly recommend Ruby on Rails. It's a great tinkering language, and it comes with great tools to "just get something on the page" and then specialize it from there. It also has a great example of good architecture for webapps in a highly dynamic language. Very good platform for "web 2.0" kind of stuff, if you'll excuse the buzzwords. It should be both new enough and familiar enough to pique your interest, I think.
Developer Tools.
Choose a new language and/or platform and create some small application/system that will help you crank out, validate, improve, etc the PHP, MySQL and Javascript code that you need to produce to keep yourself fed and a roof over your head.
You could get some Java experience by using Google's GWT. It allows you to write javascript code using the Java language. The GWT compiler will compile your Java code down to highly optimized javascript. It has many more useful features as well.
You could try Python or Perl, instead (or with) PHP. They should be fairly easy to integrate with your existing Apache/MySQL/PHP setup.
And you could always swap MySQL out for PostgreSQL. It too fits well into that world.
Structure and Interpretation of Computer Programs, which is available online, is covering about every major programming concept, including functional and logic programming style, lazy evaluation, DSLs, concurrency, continuations, representing state and OOP. The programming language used in the book is scheme, a very abstract language with minimal syntax.
While you will probably not do any projects in scheme itself for money, the concepts you will learn apply to the whole field of programming. You will see MySQL/PHP/Javascript with different eyes. To me and other people it was the red pill of the matrix movie...
Step out of that set of technologies for a while, and pick up a functional language and play - Haskell if you want to stay in the open source world, or try F# in the .NET domain. Both have interactive interpreters (good for experimenting!) and have really stretched my mind coming from a largely PHP and Java background. It will give you a fresh perspective on your (L?)AMP work.
I hear second-hand that functional-style programming can be done in JS, but I know nothing about it. That might be another way to look at JS for you.
You should have a look at haXe, it is a quite unknown and new language, but it could perfectly fit you needs:
If you are not afraid to learn something new you should take a few hours and give haXe a try.
Instead of using a new technology why not use a current technology in a new scope? I'm using JavaScript since 6 years now, and I'm learning new wonderful features of this language on almost a weekly base. In fact, it's almost a full-featured functional programming language, and you can have fun with closures and prototypes (which is something that comes just recently in PHP 5.3).
Suggestion: Try server-side JavaScript.
There are several possibilities, for example the highly praised Node.js or the Firefox addon POW. You will get a complete new view to a language that you might mis-interpret as a "do some clicky stuff" kind of childrens' language.
A few things to consider:
execTry integrating some XSLT into your stack. It's complementary -- you keep on using your existing host languages (the XSL extension for PHP, or one of the JavaScript engines). XSL requires a very different way of thinking, and writing, your code.
It's not a full-blown functional language, but contains many of those concepts. And, it's a practical skill -- there's quite a bit of it floating around out there, and if you can deal with it, there's money to be made.
I'm currently maintaining a couple of ASP applications that make heavy use of it. I HATE it, but I'm glad I had to learn it. There's a sizeable community of people who LOVE it (they're crazy ;-) It would certainly meet your desire to try something different.
Try PostgreSQL for a better SQL database. Very user-friendly, much more capable than MySQL.
Implement a PHP extension in C or C++ (Extension Writing Part I, Wrapping C++ Classes in a PHP Extension)
edit:
Try a different web server, like lighttpd, bozohttpd or mongoose
Definitely try PostgreSQL. I am just starting to get into it and I can't believe how much more than "data storage" you can do with a solid database.
Instead of programming your logic in the language - try using the database to handle your logic with stored procedures, functions, and views. Hey, they even support recursion!
If you want to try a new technology, try a php MVC framework like CakePHP or Symfony
MVC is a very interesting style. I'm just discovering with django, which I'm loving. Which i also recommend if you want to get away from php and play with python. It's very easy, and django in particular has great documentation.