This cross-fade slide show created by Millstream is a very nice script. It requires the use of Prototype and Scriptaculous. Cross-fade comes with 4 transitions that you can select and you can have the slideshow start on your own. There is also Button Controls so you can go through the slide show manually. Cross-Fade is now on in version 4.1 so it is still supported. Since Flash gets lots of bad rap for SEO this would be a good replacement.