Check out Arles at
http://www.digitaldutch.com
It builds static pages, and has the slideshow stuff built in. Check out
http://www.primanudes.com/nude-art-galleries
If you want something dynamic, Coppermine works very well. Primanudes is coppermine -
http://www.primanudes.com
Coppermine is open source. A new version should be coming out soon. If you plan to modify it, don't use the current version - it sucks for mods.
Gallery from Menalto is also good.