The software behind this gallery is written in PHP by me. It is OpenSource and free. You can download it from github. Note that it is still under development.
For a fast start download this file and upload it to a directory containting images.
There are modules to improve galleries. For example modules to display non-image files and text, to zoom on images that don't fit in the view and to show EXIF infos.
In this gallery I'm using the ImageInfo module to provide information about the creator of an image and the license which are saves via EXIF/IPTC in the file itself. The LargeAlbumView module displays large images of an album on one page. The Zoom module gives you the ability to view large images better. Text module is for having texts like this one you are reading right now and Link module helps placing image links in the gallery.