Fire Gallery is a simple and easy to use application. Upload one file, tell it where your images are and it will create thumbnails, order them by newest first and display them in pages on any part of your site.
Lightbox compatible.
Lots of options to customize for your needs. Once set up, Fire Gallery is as quick as having a static html page gallery. It is a very lightweight script, only 10kb.
Supports jpg, png, gif