What're the essential web languages for a new developer?

Start with Javascript and its most badass library, http://jquery.com/. You'd be amazed what you can do with just HTML, CSS and Javascript. (You mentioned Java several times ... do you mean Javascript? Aside from the name, the two have little to do with each other. Or do you mean Java applets? If it's the latter, I'd focus a lot more on the former. Java applets are nowhere near as prevalent as they were a few years ago.)

Honestly, as much as I hate to say it, the most important language to know for the web right now is Javascript. The cool stuff on the web is all happening on the client-side, not on the server-side. For a server language, you'd be well served by Java, PHP, or Ruby as you mentioned. I'd avoid Java unless you had a particular reason for it. I'm also partial to Ruby over PHP, but PHP has its place if you just want to toss up something simple. But you can do so much with Javascript these days, especially with things like Gears and HTML 5. And like Nelsormensch said, jQuery rocks.

Time to get started on Javascript, then! A Q, however- Javascript can obviously do a lot of fancy, pretty things that HTML/CSS alone cannot. However, isn't there a temptation here to bloat one's code with pretty tricks? Is there a place for best practices/live examples to understand where best to use Javascript?

It's not a pretty language, and there's a LOT of bad code floating around out there, but PHP is pretty much the 'English' of web development these days. Most everyone speaks it, and it's stupid simple to experiment and learn with tools like MAMP and WAMP. Languages like Ruby and Python are sexier, and if you're really passionate bout clean, elegant code the communities around those tools will probably be more helpful. As others have said, though, learning JavaScript and understanding the DOM -- then leveraging it with a library like jQuery -- will put a lot of really crazy stuff in your reach.

I'm leaning towards the opinion PHP is probably the best path to take. There are some very compelling reasons to use both Java and Ruby on Rails, but in terms of the ease with which you can create and deploy dynamic web pages, PHP is probably the simplest proposition. Certainly you'll find much wider support for PHP out of the box among hosting companies, if only because it's available by default in so many Linux distributions. Another technology to consider would be Microsoft's .Net framework. It's pretty damn good according to a lot of people I've spoken to, although it's somewhat more platform-dependent.

Any suggestions on where best to start with PHP? I'm open to a good ol' paper book, but I've certainly found web resources to be considerably more useful

javascript and actionscript3 on the client. php, python and ruby on the server. i really like working with java, but there's a lot of boilerplate and coding overhead. and if you want to process text, you'll get carpal tunnel in a week. if you really want to make yourself interesting, you'll get into the geoweb. check out http://geoserver.org and, of course, google and yahoo maps. i agree with Nelsormensch about java applets. flash has largely supplanted java for things that are best done in that way, and the new VM is very, very fast. the actionscript3 API is vast and still expanding, with the latest player offering native 3D transformations better filesystem access. that's on top of raw sockets, streaming HD video, etc.

Python. it's way cooler than PHP.

Sorry, I should elaborate. Python is a much, much better language on a fundamental level and has lots of interesting libraries and frameworks available for it as well as interesting execution environments like Google's AppEngine. Python's built-in data types are a real joy to work with.