Web Design Languages?

As a web designer, what scripting languages should i know?
I already know HTML, CSS, JavaScript, and PHP.
What am i missing?
Should i learn Java, C++, Python, Ruby, ASP and stuff like that too?

It's always good to know as many languages as possible. Of course you won't have the time to master everyone, but you don't need to - that would be time prohibitive.

PHP is a good all rounder I think, but last time I looked there were more jobs for ASP programmers. Employees have the idea that only ASP is capable for large scale systems which is not entirely true. To develop in ASP you need to know either C# or VB.

Lots of enterprise level developers use Java to build their web applications. For small websites it's probably not practical because Java hosts are more expensive.

You can build websites with C++ if you really want but I haven't seen anyone do that. C++ is the industry standard for game development (with Java catching up), but it's pretty much non-existent in web development.

The following talks about Frameworks:

Ruby (on Rails) is the "sexy" and all hyped-up solution at the moment, but you might have trouble finding hosts that support RoR. It's probably more hype than substance.

Python with Django is another popular framework similar to RoR.

CakePHP is a very popular framework for PHP.

It's a good idea to look into frameworks because they do help you make better, more structured code. A framework aims to help speed up development time, but also acts as an application design teacher.