Recently I was asked to put some input into a site for a photographer. They wanted something easy to use and would look and display images at their best.
There are a few alternatives one can use. In my opinion a flash based gallery is a good option. For this particular site I decided the gallery at http://imagevuex.com/ would be ideal. Its highly configurable and editable. Also it comes with the source files so you can tweak until your heart is content.
There are free flash based web gallery’s too. And also lots of php / mysql versions.

Popular free flash gallery
http://www.airtightinteractive.com/simpleviewer/

Another free flash gallery
http://www.webworksite.com/photogallery.shtml

Simple php thumbnail and page generator
http://www.flash-here.com/downloads/fhimage.html

Also not to forget Coppermine photo gallery php based
http://coppermine.sf.net/