I just installed a plugin made by Kjell Bublitz. It enables you to use the excellent Lightbox script made by Lokesh Dhakar. This plugin was very easy to install (just upload and activate). It works very well and integrates into WordPress perfectly.

You can find the plugin here:
http://www.m3nt0r.de/blog/lightbox-wordpress-plugin/

Here’s few demo images:

Single image

Series of images