My experience relevant to multimedia is rather limited; I'm here to learn. 

Using the term loosely, I've dabbled in educational uses of multimedia in my WebCt courses. My main concern has been to seamlessly integrate the audio component of listening tasks and quizzes such that the sound file runs automatically, once only, and concurrent with the presentation of the questions.  The idea is to replicate in a self-access course the conditions found in the listening segment of the IELTS examination.

In terms of animation, I've tried to get my head around Flash.  I had limited success, and promptly forgot most of it...although I can see that it is an excellent tool in the right hands.  It's a challenge that has to be tackled during this course.

I'm also experimenting with Camtasia Studio.

 

The most important characteristics of well designed multimedia, in my opinion, are:

• Purpose: I detest flashy, wiggly things with no apparent use... (I can forgive the banner ad at the top of this page because it's the price of server space with Tripod)
  
• Speed: bandwidth and wait time; if it makes me wait, it had better be worth it
  
• Clarity: it shouldn't be a strain on the eyes
  My two examples of multimedia on the worldwide web are available by clicking the images at right