Even though i have not made so many applets, but i am aware of advantages linked to it. If you have done maths in your academic life, and if you go on internet for help you will see some kind of animation like drawing a graphs when you put the equations in. Few months ago i used a java applet for music processing. Hence applets provides an easy user interface so that user can understand the concept behind it. Unlike normal GUI applets can be opened inside a web page to be precise in html pages
:)