This takes a while to download all of the classes, so be patient -- put your mouse over the applet and look at the bottom of the browser for status.
Getting Java: If this isn't working in Microsoft's Internet Explorer, it's because by default it uses an old, buggy Java implementation. I hate to make you do this, but you may have to download and install Sun's Java Runtime Environment Plugin (J2SE JRE) at http://www.java.com.
Using the Applet: Chose a sign-convention from the four equations (see how two are not plane waves). Drag the sliders to set the amplitude and frequency. Drag around the graphical display area to set the wave number (momentum) vector. Watch the phase at the origin move around the complex plane in the top right.
The code is liscenced under GPL. It's not complete or presentable yet. You can browse the java directory including source at /java. Archive of the entire directory is java.tar.bz2 (10 MB)