In Java 1.4, the AppletContext object now has getStream and setStream methods(). Can you not use these to stream data (i.e. text messages) to your applet.
// get the AppletContext
java.applet.AppletContext ctx = getAppletContext();
// get a URL which will write data to its outpurStream.
// get the InputStream to this URL.
InputStream is = url.openStream();
// set the Stream
ctx.setStream("dataStream", is);
After the above has been done, in the call to init(), create a thread that reads from the inputStream. This needs to be in a thread, as the read will be blocked until something is read.
When something is read, set the text in a "status" panel of your applet.
These are simply some ideas, as I haven't attempted it myself, but I gues this is how stock market prices are relayed to browsers, and news updates sent to news banners.