One CGI which you just drop into a directory containing images. It does everything else. Do Flickr-style tagging, RSS feeds, etc, etc. CGI is setup.cgi, which creates files and writes a "havebeenrun" flag file, and checks for that so it can't be run twice.
Integrate technorati tags, FLickr tagging, so you can see who else has your photos. Like a decentralised Flickr, really.