You mean something like this:
http://www.bishopimage.com/

That site belongs to a friend of mine, and he used a commercial Flash script. He said it wasn't very expensive and it was easy to set up and use.

Now...

I looked at this, and I *could* do the same thing in JavaScript. No need for Java. Making it work cross-browser is a little bit of a challenge, but it's not impossible. Probably a lot more code than it would be in Flash, though.

The fade-in, fade-out is a bit tricky, but you can see it working (cross-browser) at this site that I did in June:
http://www.artsofsnohomish.org/index_july2008.html