The TinyWebGallery is a free PHP based gallery that is very easy to install, extremely user friendly, does not need a database (uses xml files) but still has all the features you should expect. Besides the features you find in most other galleries TWG has - DHTML navigation, Keyboard navigation, Protected galleries, Full screen mode, Remote picture support- Text and image watermarks, and Full Admin backend. Check out the demo or the list of all features. Maybe TinyWebGallery is the gallery you where looking for so long.
||Windows XP, php 4.3.x - gdlib 2.x