Stu,
Here's a link to a short thread about these animations with several examples.
http://www.nwpphotoforum.com/ubbthreads/showflat.php?Cat=0&Number=7820&an=0&page=1#7820 I use EZ Gif Animator, a simple program available on the web (see the thread I mentioned for more details).
AND NOW.... all eyes on the duck:
