I recently came across 4 very nice jQuery plugins for slideshows and galleries. Actually, I found a lot more, but those are my favorites:

1. Nivo Slider (slideshow)
2. jqFancyTransitions (slideshow)
3. jQuery Cycle Plugin (slideshow)
4. Fancybox (gallery zoom)

I decided on Nivo Slider for a new project (www.gaastra-store-fehmarn.de), simply because it offers beautiful captions with links and images, which I´ll need for the second project www.loftfehmarn.de.

If you don´t need those wild animations, but are looking for a cool Lightbox alternative, check out the Fancybox plugin, which I use on surfspot.de.