One way you can do this is by creating a marquee and floating a semi-transparent image at its edge:

Any of the ones you found are fine, or use this one built in jQuery: http://remysharp.com/demo/marquee.html

Here's a fading image: http://www.collylogic.com/scripts/fade.png

Here's the source where you can see actually SEE the fading effect on the above image

The advantages of doing it this way is that you're not doing any expensive processing in javascript. You also have a wider variety of scrolling to choose from without having to worry about when or where to fade.

The disadvantage is that semi-transparent pngs need a hack to work in IE6. But since it's just eye candy, I'd imagine those few IE6 users won't be impacted that much.